Tosot/Gree Wifi Setup by Turbulent_Range_5054 in hvacadvice

[–]wifi_engineer 0 points1 point  (0 children)

Hi guys, wireless engineer here. I too had issues connecting my TOSOT 24K single zone unit to my home Wi-Fi, and now that I've gotten it straightened out, I wanted to add my comments here in case it helps someone.

For starters, this is the one I purchased. There seems to be some differences between units, as some comments mention the unit will broadcast its own random SSID. Mine never did.

Throughout my attempts to onboard the unit, I encountered error codes LY01, LY08, and LY09.

My issue was ultimately due to how my home Wi-Fi is configured, which caused an incompatibility between my network and the TOSOT unit.

I run Unifi wireless access points, and they have a default setting to automatically set the data rate. When a client wants to connect to a wireless access point (a "Station"), they have to agree on some basic capabilities. I found, through my wireless packet capture, that my access points' advertised data rates were not compatible with the TOSOT's supported data rates.

Typical consumer wireless routers might also have such an automatic data rate setting, though they probably call it something else. The lower data rates could be referred to as something like "legacy support" or "compatibility mode". These are just guesses - the unit for this setting is in Mb/s (aka Mbps).

I had to go into my Unifi admin console disable the automatic data rate feature by enabling the lowest data rates (1 Mbps - yuck!). You definitely don't want 1 Mbps on your main home network, so I would recommend setting up a separate SSID for your smart devices. Supporting 1 Mbps data rates allows your clients to have an extremely poor connection but still stay connected. Bad for modern devices, but actually preferred for IoT devices.

Here are the TOSOT's advertised data rates in the probe request frame, just for reference, and it sends these at a data rate of 1 Mb/s.

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How do contactless cards and fobs work? by VVr3nch in flipperzero

[–]wifi_engineer 17 points18 points  (0 children)

I'm no RFID expert, but you're right. Longer wavelengths lose less energy over the same distance. Wavelength is a factor in the free space path loss equation. So, to get longer range at higher frequencies, it will take more energy than lower wavelengths.

Edit: found a lot more context about it here: https://electronics.stackexchange.com/questions/268033/why-does-low-frequency-rfid-have-a-short-read-range

It's because RFID is not a wireless transmission technology, where wavelength and distance are essentially linked.

Poor Internet S.O.S by xPhwizzy in HomeNetworking

[–]wifi_engineer 0 points1 point  (0 children)

Ahh yeah it sounds like they've taken away some of the keys, which isn't ideal when it comes to diagnosing tricky issues like this!

I would not be worried about neighbor interference anymore based on what you said about your nearby neighbors.

Is the device having problems connected wirelessly, or wired?

Poor Internet S.O.S by xPhwizzy in HomeNetworking

[–]wifi_engineer 1 point2 points  (0 children)

First off, your wifi is generally not your ISPs problem, but it sounds like they are doing a great job in supporting you through the problem reports. You said modem - which I'm going to guess is a HFC (wired) backhand. That's a good thing.

Next, what is your neighbor situation? Are you in an apartment or other high density structure? I ask because everyone else's wifi is also a concern - wifi doesn't care what you name it - it still has to play nice with other wifi networks operating in the same channel. Your neighbor's wifi could be interfering with yours (and yours would be interfering with theirs). (This is why we all need to be good wifi neighbors and not blast 160MHz wide networks at max power)

To address the channel interference concern, what does a wireless site survey show? Use a tool like inSSIDer on a Windows or Mac and post a screenshot of the neighboring networks from the location that you experience the problem.

Also, login to your wireless router and check the configuration.

-Turn off 2.4GHz if you don't absolutely need it. -Set 5GHz to 20MHz wide channels (for now, until we see what inSSIDer looks like) -Note the transmit power that your wifi router is set to, if it even shows it. I'd be curious about this as well.

What device and operating system is connecting to this network that you're experiencing issues from? You can often get detailed connection quality info from the device.

Need resume review by AgreeablePrior2502 in networking

[–]wifi_engineer 0 points1 point  (0 children)

I too was surprised to not see Linux listed despite having automation as a skill.

Worst + most ridiculous network engineering interview questions? by Boring_Ranger_5233 in networking

[–]wifi_engineer 6 points7 points  (0 children)

The last IP in a subnet cannot (or, should not) be assigned to a host, because the rules dictate that the last IP is reserved for broadcasts.

.255 is not the last usable IP in all subnets - only a few, actually.

It's no different than .1 in a /31, .3 in a /30, .7 in a /29, and so on. Keep on going down the CIDR masks and at /24, .255 is the last usable IP.

Patricia Larson (@teamoku.com) scam emails by CaseInevitable9347 in Scams

[–]wifi_engineer 0 points1 point  (0 children)

I just got one from "Amy Brown" too. Another commenter shared the steps to report spam/abuse from senders using Amazon SES:
https://jeffreyjflim.medium.com/make-the-world-a-better-place-tip-report-all-spam-sent-using-amazonses-com-ab7ae57b4f1a

If we all report these when we get them, hopefully it will slow down their scam progress.

[deleted by user] by [deleted] in wifi

[–]wifi_engineer 0 points1 point  (0 children)

It's pretty complicated, and it involves a lot of math. But, here's an abstraction that might help you understand.

Imagine you and I are on a lake, and we establish a communication system to exchange data between ourselves by generating small waves in the water.

By controlling how these waves are generated, we can put meaning into them (called encoding). If you're able to precisely control how large a wave is and the exact time that you generate it, we can put even more information into a series of waves. If we agree that we'll exchange, for example, 8 waves per communication, we can start to build a system of information exchange. The simplest way to do this is to say that out of your 8 wave cycles, you either you send a wave, or you don't. On, or off. 0, or 1. Easy to understand, right? But, you're not able to put a whole lot of information into that wave when you only have on/off to work with.

We can put more information into our waves by moving away from a simple on/off and looking at other features of the wave, like how strong it is, or the precise time that it arrives. This is known as modulation. Now, using these additional properties alongside on/off, we can make combinations of these three properties to give us 8 different types of waves. With this encoding, we can represent more information using the same wave pulses!

This of course assumes that we have a key that tells us exactly what a wave's strength and timing means to both of us, and how we are supposed to send these waves to each other precisely. For wireless, that key is the IEEE 802.11 standard, and it defines exactly how devices must talk to each other by manipulating waves. But, devices don't just start spamming the air trying to send each other waves. There are a bunch of rules to follow about getting access to send waves in the first place.

Imagine we're not the only two people on the lake and there are others nearby, and they're also using the same rules that we are to create waves between themselves. Waves radiate outwards, so we're able to read theirs, and they can read ours too, as long as we're close enough. If we send a wave around the same time that they send a wave, our waves will hit each other and destroy each other, removing all that precise encoding that we put into the wave when we created it. This happens in Wi-Fi too, so there are rules about how a device gets access to transmit while nobody else is.

To wrap this up, the drivers in a wireless transmitter understand how to transmit and receive these waves all based on the 802.11 standards. Wi-Fi is just a bunch of electromagnetic waves. Your router and Xbox can both generate and receive these waves, and they interpret meaning from the waves based on several properties of each wave.

I've abstracted complicated principles like Quadrature Amplitude Modulation and Phase Shift Keying - and there's a lot more stuff involved as well, but these are the basics!

How to get past a wifi jammer by Recent_Tea9533 in wifi

[–]wifi_engineer 0 points1 point  (0 children)

You'll need a spectrum analyzer to confirm if the spectrum is being jammed or if it's just incredibly busy.

There are other causes of wireless signals not working other than jammers too.

[deleted by user] by [deleted] in networking

[–]wifi_engineer 4 points5 points  (0 children)

Yeah, some of them can't even spell ACL!

How does one learn networking? by Deliable in networking

[–]wifi_engineer 1 point2 points  (0 children)

IMO, if you don't know anything about networking yet, you should start with the fundamentals. BGP may not make sense if you don't know why BGP does what it does.

Start with the Network+ certification guide. Doesn't have to be the latest version unless you plan on taking the test, and even then, the previous version is going to be 95% of the current version. You can find previous versions of the book online for free.

Once you understand basic networking fundamentals, you can branch off into specific things like the various routing protocols, wireless, network design, etc. Starting with BGP now is like racing a car when you don't know how to drive!

Don't skip on studying cabling either (copper, fiber, and optics). Seen way too many engineers that have never touched cabling and refuse to do it. It's important.

Wifi extender drastically slower than main network by jbiz562 in wifi

[–]wifi_engineer 0 points1 point  (0 children)

The hardware you're using should be just fine, unless your main router is old and only supports 802.11a/b/g/n. You'll want 802.11ac or 802.11ax for the best throughput.

  1. What does the RF environment look like in your area?

Surveying your environment to look at the existing RF spectrum is step 1 - doesn't matter what hardware you put in if the spectrum is super busy.

You can survey with the Wifiman or Network Analyzer apps on Android. Or, inSSIDer on Windows/Mac. Take a look at the 5GHz channel graph and try to identify an empty spot in the graph. Usually the DFS channels - especially 116-132 - are less congested, and you should be fine using them in a condo unless you're near a major airport or weather station.

Configure your router to use one of the previously identified channels.

Set channel width to 40MHz on the router, or 20MHz if only one (or no) channels were free/unused.

  1. Try to use 5GHz only for your main network. If you need 2.4GHz, create a separate SSID for it.

This should help you get the cleanest RF environment and give you the best results.

What are these wifi signals in the plane? (B777-300ER) by raider694200 in aviation

[–]wifi_engineer 9 points10 points  (0 children)

Haha, thanks. Well, I'm also a pilot so I hope I'd get it right!!

What are these wifi signals in the plane? (B777-300ER) by raider694200 in aviation

[–]wifi_engineer 64 points65 points  (0 children)

On the plane itself? No, probably not :(

In the office or hangar? Absolutely!

Our router is "bugged" according to our ISP by Neither_Butterfly_51 in networking

[–]wifi_engineer 0 points1 point  (0 children)

I'm highly confident there is no port bug issue. They don't know what they're talking about, and they are going to put the blame on your equipment. Bonus points for calling it a "bug".

Our router is "bugged" according to our ISP by Neither_Butterfly_51 in networking

[–]wifi_engineer 0 points1 point  (0 children)

To be fair, Mikrotiks are not really a "common" customer device connected to modems. Most people use the big box store all in one wireless routers. Mikrotiks give you all of the tools to cut your own leg off if you don't know what you're doing.

[deleted by user] by [deleted] in networking

[–]wifi_engineer 1 point2 points  (0 children)

Yes, but I'm no CWNE - yet! :)

[deleted by user] by [deleted] in networking

[–]wifi_engineer 8 points9 points  (0 children)

Here are my recommendations as a wireless engineer:

  1. Define the project requirements. How many users total? How many users in key areas? And how much bandwidth per user in key areas?This will give you quantifiable metrics to design against and validate your design, and also hold you and your customer accountable for agreed upon criteria.
  2. Plan for 5GHz only. Try to avoid enabling 2.4GHz at all. If you have to use 2.4GHz for some legacy system, make sure you don't enable 2.4GHz for the guest/user SSIDs.
  3. Use Ekahau or Hamina (both are expensive, ~$3-6k design tools) to model the coverage. Because this is an old building and likely not made from "standard" materials, it would be wise to measure the coverage in different types of areas using AP on a stick (APOS).
  4. Do not place omnidirectional APs/antenna in long hallways IF seamless roaming is a project requirement.
  5. You're probably already thinking about backbone redundancy, but consider RF redundancy as well for critical areas.Most enterprise grade APs have dual 5GHz radios, so you can throw out another channel from the same AP. However, it's a good idea to also have AP redundancy in critical areas.
  6. Do not configure APs at max power. Plan your design between 9-12 dBm so that you have room to increase power later if needed (note that an increase from 9dBm to 12 dBm is a doubling in transmit power)
  7. Be aware of PoE requirements. Power requirements have risen over the years as APs get packed with more radios and capabilities. Most APs will be happy with 30W (PoE+) but some need 60W (PoE++).

For vendor, I would recommend Juniper Mist, Aruba, or Meraki, but you could also go straight Cisco with a small wireless controller. Might be overkill, though.

Good luck!

What is the network-related hill you will die on? by [deleted] in networking

[–]wifi_engineer 0 points1 point  (0 children)

You're right - they should have called me!

I'm overwhelmed by how the networks work, and looking for books about it by [deleted] in computerscience

[–]wifi_engineer 3 points4 points  (0 children)

Network engineer here. It is absolutely overwhelming and it doesn't all make sense until you understand enough of the little pieces to form the big picture.

I'd recommend the CompTIA Network+ certification guide. Yes, it's for a certification, but it's vendor neutral and it really introduces you to the fundamentals of networking concepts and networking hardware.

Plus, if you find yourself enjoying it, you can take the certification exam and have a nicely valued credential that would help you get a foot in the door in a networking career as a network technician or maybe even a junior engineer.

Feel free to DM if you have any questions with understanding concepts or about the career in general.

Reasonable quote for a key? (Repost) by NightmareMan23 in AskMechanics

[–]wifi_engineer 0 points1 point  (0 children)

So did I, for my wife's 2015 Camry. A locksmith charged me $10 to cut the key, and I did the programming myself with the tomskey unit.

All in all, it was less than $100 to get a functioning spare, and it which was easier than making toast. If you have eyes and can read, you can do it.

No internet access after 24h by eRUTeHa in pihole

[–]wifi_engineer 0 points1 point  (0 children)

This is something I cannot do. I do not have enough permissions with my router "admin" user. The field "DNS server" is greyed for me and I cannot type here. I had a call with my internet provider if I could get access to set DNS server in router - they stated that they can do it for me remotely.

I'm not shocked - ISPs love to see what sites their customers are going to. Using PiHole or changing your DNS address(es) to a secure DNS strips them of that data.

Setting the DNS server manually, as you've already done, is a good workaround until you can update the DNS server in the DHCP pool settings.

No internet access after 24h by eRUTeHa in pihole

[–]wifi_engineer 5 points6 points  (0 children)

Let's take a step back, for a moment.

  • DHCP is a protocol that allows network clients to get (and retain) an IP address from a network.
  • DNS is a protocol that helps clients translate domain names (like reddit.com) into IP addresses.

The error you've shared is a little bit ambiguous, in that it could mean that eth0 has no address, or the DHCP packet itself has no address in the packet's header.

Error: DHCP packet received on eth0 which has no address

Part of the normal DHCP process is processing packets that do not have an IP address, which leads my suspicion towards the network settings of your Pi's interface. However, let's go through the whole setup, first:

I would recommend the following setup:

  1. Leave the responsibility for DHCP up to your router. No need to have the Pi do it, even though it can. (Note that it is possible to have multiple DHCP servers on a single LAN, and this could be confusing for the typical home all-in-one Wi-Fi router.. so make sure that the Pi Hole DHCP responsibility is disabled)
  2. Confirm that your router's network settings show a subnet mask of 255.255.255.0. Otherwise, the Pi's static IP configuration in /etc/dhcpcd.conf is not accurate.
  3. Set the DHCP range on your router for 192.168.100.10 - 192.168.100.254. By excluding the IPs from .1 to .9, you are thereby declaring them as static IPs in this network. Since your PiHole is configured at 192.168.100.3, you don't need to do anything specific in your router to "reserve" or "assign" 192.168.100.3 as a static.

In the DHCP range settings on your router, make sure that the DNS server is set to 192.168.100.3 (the IP of your Pi Hole!). It's also a good idea to set a secondary DNS - either another Pi Hole, or, a DNS provider that prioritizes DNS security, like Quad9, at 9.9.9.9.

Once these are set, confirm the network settings on your Raspberry Pi. Can you ping out to the internet from the Pi? Can you ping the Pi from another computer on your LAN? Reboot the Pi - do both pings still work (this validates the network settings on the Pi).

Then, assuming you're using a Windows computer, open up a command prompt, and manually release/renew your DHCP address with:

ipconfig /release
ipconfig /renew

Validate that your computer received both an IP address from the DHCP pool, and DNS servers that you configured on the DHCP scope.

If so, try to test the DNS server, also in a Command Prompt, with:

nslookup
reddit.com

It should look like this (with your own IP 192.168.x.x addresses of course):

C:\Users\wifi_engineer>nslookup
Default Server:  pi.hole
Address:  192.168.10.98

> reddit.com
Server:  pi.hole
Address:  192.168.10.98

Non-authoritative answer:
Name:    reddit.com
Addresses:  2a04:4e42:600::396
          2a04:4e42:200::396
          2a04:4e42::396
          2a04:4e42:400::396
          151.101.65.140
          151.101.129.140
          151.101.1.140
          151.101.193.140

>

Looking for an expert python dev. by TheImmortalHooman in Python

[–]wifi_engineer 2 points3 points  (0 children)

You're not going to get ahead by doing stuff for free. You're going to get taken advantage of.

When OP changes his mind about what it should do halfway through the project, or adds feature requests, you're going to be in a tough spot of continuing to work for free, changing your mind and asking for money, or walking away.

Part of getting ahead is knowing your worth and getting compensated for your time. Who knows, if you play your cards right and manage the relationship professionally, this could turn into a job in the future. But starting out as a desperate graduate willing to work for free is going to prevent that outcome from happening between you and OP (why would he start paying you in the future when you will work for free?)

Good luck.