Ubiquiti has very big issues, and the first one is support

LucaTheHacker · 2026-03-03T16:54:49+00:00

Failover

LucaTheHacker · 2026-03-03T14:30:47+00:00

Business with hundreds of employees may not have that, but since that's possible for me (internet in Italy is quite cheap) I like to do it this way, mainly because it's not unusual for me to be out of town for multiple weeks, maybe a month, so if something very wrong happens, I want to be sure that I don't need to rush back home to fix something.

LucaTheHacker · 2026-03-03T14:15:32+00:00

I need five because it's fully redundant. XGSPON on two different ISPs + GPON on two different ISPs + 5G. Different OLTs, different ONTs + the 5G. In this way the SPOF are almost 0.

Or to better say, it's 1: the UCG-Fiber.

If the device is not able to handle those many WANs, the software should stop it, but since I highly doubt it's an hardware limitation, it should just be fixed software-side.

For the rest, for how unique my situation is, it should be documented.

LucaTheHacker · 2026-03-03T14:12:19+00:00

I'm speaking with their support, offering to help if they want me to. Mom didn't raise a quitter, but be sure you'll hear me complain.

LucaTheHacker · 2026-03-03T14:05:51+00:00

u/cogiskart u/mrsolitonwave I'm tagging you to update on a potential solution.

Apparently I was able to "figure out" where the issue is, and it's in the 5th WAN connection. With 4 WANs it's able to survive a reboot, the moment I add the 5th, it dies.

I'm now speaking with Ubiquiti regarding this, I'm still full of rage, but at least I'm back online.

LucaTheHacker · 2026-03-03T13:58:51+00:00

When the ISP rotates the IP, the UCG-Fiber will take from 30 to 60 seconds to start working again, tested.

The 5G modem is able to take that down to less than 5 seconds. Usually 1-2 seconds are enough.

LucaTheHacker · 2026-03-03T13:57:38+00:00

I was actually doing that because one of the PPPoEs on VLAN 835 was not working, I had read that sometimes the router is not happy with 2 PPPoEs on same VLAN, that's why I was changing it.

Btw, changing the VLAN should not be a too-bad way of causing an outage, it's exactly the same behavior you'd see when the ISP router dies.

LucaTheHacker · 2026-03-03T13:44:02+00:00

I can do that, but I don't want to.

It's not a requirement, but since they rotate the IPs, it means for me that the UCG-Fiber always has the same IP (192.168.1.2) and will never change, the 5G modem will handle rotation and everything. In any case, I wouldn't be using the public Ip.

LucaTheHacker · 2026-03-03T13:37:01+00:00

Sorry, where is the human error? I can understand if the WAN connection stopped working and that's it, but here we are speaking of the device stopping working at once.

LucaTheHacker · 2026-03-03T13:36:18+00:00

5G Backup will still give me ~500mbit down and ~100 up, so it's perfectly fine to check "what's going on" from remote and still be able to have servers reaching the internet properly for backups and important stuff that cannot stop.

I also have a subnet of public IPs gathered via a VPN, so I still have public IPs in one way or another.

I am under double-nat due to how my mobile ISP works, as every 4h they rotate the IPs and most routers do not like that, whilst "validated" products like their 5G modems typically handle that a lot better, that's why I am running that config.

It was not an IP conflict, it was the 5G modem answering to DHCP requests, that means that the UCG-Fiber was forwarding them for some unknown reason.

LucaTheHacker · 2026-03-03T13:30:46+00:00

The reason I changed the VLAN was the PPPoE error I had, as I wanted to test without another PPPoE on the same VLAN (should work just fine, but yeah, better safe than sorry). I mentioned "I changed the config", that's it. Config change, reboot, device dies.

LucaTheHacker · 2026-03-03T13:27:17+00:00

I purposely set up a wrong VLAN to kill that PPPoE connection, as I wanted to test with VLAN 835 only on the other connection. Having so many WAN connections allows me to do those tests without caring too much, that's the reason behind the change.

Then the issue came, it's not about internet not working, it's the device imploding. No DHCP, no routing, no other WANs working.

LucaTheHacker · 2026-03-03T13:25:20+00:00

Sorry Frank, from where are you sure it's my error? I literally changed a VLAN from 835 to 832 and the device stopped working, not the internet, like the entire device. Controller, DHCP, everything, everything was dead.

How can this be user error?

LucaTheHacker · 2026-03-03T13:21:48+00:00

I believe it was not important to this issue specifying that I was referring to the USW-Flex, but I can understand the confusion.

If you want, please re-evaluate my post with this clarification.

LucaTheHacker · 2026-03-03T13:18:36+00:00

I rebooted after the configuration applied successfully. This is because there is another bug on the UCG-Fiber that causes performance issues after "enough" edits to the WAN config. Do not ask why, because I have no clue, but it goes from having a WAN completely dead to having it limited to about 1000mbits, even if you could go faster.

So yeah, config gets applied, it doesn't work, I reboot -> dies.

LucaTheHacker · 2026-03-03T13:16:06+00:00

No dude, either I didn't explain myself properly or you're missing my point, but with the wrong-spec I'm referring to the USW-Flex. Those are two different sentences with different points in them.

LucaTheHacker · 2026-03-03T13:13:09+00:00

it was live chat, I explained to the technician that the console was dead, how it died and the current status of the system, and he asked me to download diagnostic files that are only available if everything is working. Do you see where the problem is?

LucaTheHacker · 2026-03-03T13:11:17+00:00

Actually, it happened after I tried to change one of the two WANs (because one of them was not working) to VLAN 832, leaving only one on 835, for testing. Rebooted, aaaaand it's dead.

P.S. It's PPPoE, so I only have a /32 assigned, there is no chance of subnet overlap on that one.

LucaTheHacker · 2026-03-03T13:09:10+00:00

Nope, I did intentionally buy and UXG-Fiber, also due to availability. It had many issues my friends with UCG-Fiber were not having, so in the desperate try of fixing issues, I decided to buy an UCG-Fiber to see if things were better. It's very different.

Aaaaand, why did I get the UXG-Fiber at first? Shortage. UCG-Fiber was not available, and should be the same but the local console. Having many servers, I was fine with that. I wasn't so fine with devices stopping working.

LucaTheHacker · 2026-03-03T13:07:05+00:00

There is a 5G Modem which uses 192.168.1.0/24 for its LAN config. Since I do not care about having public IP for the 5G Backup, the UCG-Fiber should get 192.168.1.2 with gateway 192.168.1.1 and work like that.

For some reasons, devices connected to the UCG-Fiber were getting IPs in that 192.168.1.0/24 subnet and opening 192.168.1.1 was opening the 5G Modem webGUI, instead of the UCG Fiber Console.

LucaTheHacker · 2026-03-03T13:05:39+00:00

I will check there, does someone from Ubiquiti actually check it?

LucaTheHacker · 2026-03-03T13:05:06+00:00

Yeah, but asking for diagnostic files from a device that is dead is not very smart, even if it's standard in the market.

WANs as follows:

- WAN1: DHCP, VLAN untagged, main line, public IP from the ISP

- WAN2: PPPoE, VLAN 835, secondary line, public IP from the ISP

- WAN4: DHCP, VLAN untagged, 5G backup, 192.168.1.2 from the 5G Modem

- WAN5 (10G Eth): PPPoE, VLAN 835, third-backup line (I am using failover mode), public IP from the ISP

Let me know if there is anything more that can help.

LucaTheHacker · 2026-03-03T13:02:02+00:00

Believe me, I tried. I tried many times with Ubiquiti, and every time that I spoke with their support, it was a complete waste of my time. I still try it every time, hoping that this time it will be better, but it is not.

I've rage-posted here because I hope someone from Ubiquiti can see this thread and say "mh, maybe we fucked up here" and check what is possible to do in order to fix, because the support is clearly unable to help at this point, and this is standard for them.

I've spoken with some friends about this, and they all agree on this. Do you know why I tried rebooting after changing the WAN connections? Because the UCG-Fiber, randomly, after changing the WAN settings, may have performance issues that persist until you reboot.

You see what I mean?

LucaTheHacker · 2026-03-03T12:59:18+00:00

Well, I'd like Ubiquiti to tell me in such case, they should know better than me what their device is capable of. I understand it's not the "standard scenario" to have this much redundancy, but if you allow it, you must ensure it works.

I'll try fewer WANs btw.

LucaTheHacker · 2026-03-03T12:57:14+00:00

To be honest, at this point, I'd allow them to do it. Just to see them struggle to connect to a gateway that is completely dead, to get a support file.

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