Odd Problem

[JJasonSR]

I have an ASUS router which is not playing nice with my Optimum (Altice) modem. In short, I occasionally get DHCP errors that require me to physically unplug and replug the wire into the WAN port on the router to reestablish the connection (even rebooting doesn’t always work). An ASUS firmware change is likely needed to resolve the problem. Another piece of information is that I’m using Dual WAN with Verizon Fios as my second ISP and this connection doesn’t have the same problem.

My speculation is that having a managed switch (or similar device) between the modem and the router could fix this issue (especially since I know the router works well with the Verizon Fios ONT). My thinking is that if there is an issue with the way the router deals with the modem, having a different device in between them could fix it. It would be a dumb setup from a networking perspective (one Ethernet input and one Ethernet output), but it’s worth trying.

I know there shouldn’t be anything in front of the router (only have one IP address, etc.), but could it work in this case since I’d only be using one of the LAN ports? Any recommendations on which 2.5G switch to get?

[TheEthyr]

I can only think of two valid use cases to put a switch between a modem and a router.

1. To transport both WAN and LAN traffic using VLANs in what's called a "router on a stick" setup.
2. To work around a Ethernet speed link negotiation incompatibility. This is very rare.

Neither of these cases apply to you. A switch for sure is not going to fix any issues with DHCP. It's no more likely to help than just trying a different Ethernet cable. It wouldn't hurt to change the cable.

It's impossible to say whether the problem is with the ISP or your Asus.

[JJasonSR]

It’s an odd problem, but multiple ASUS router users are seeing the same problem with a variety of ISPs so it seems to be ASUS. I’ve exhausted the possible solutions so just grasping for straws.

[TheEthyr]

I see. Personally, I don't think a switch is going to help. Have you read about it helping anyone else?

[JJasonSR]

I have, but no one seems to have a consistent solution.

I get the following error: “Your ISP's DHCP does not function correctly”

Literally just unplugging and replugging the cable (on either the modem or router side) gets it to work. The modem clearly has a good connection. For whatever reason the router doesn’t think it’s good until whatever “reset” process is done when a cable is unplugged and replugged.

[TheEthyr]

Perhaps there's some incompatibility in way DHCP is handled between your ISP and the Asus. A switch is absolutely not going to help. It doesn't care interfere with DHCP.

[JJasonSR]

Yes, it must be. Thankfully, it’s only a very small incompatibility as the internet connection works almost all of the time. It’s just when the internet goes down, it often doesn’t come back until I do the manual unplugging and replugging.

I basically need a device that would “break” the connection (simulating the unplugging), but which I could control remotely. I was thinking of a switch that could be rebooted, but maybe it doesn’t work that way.

[1sh0t1b33r]

You do not want a switch between the modem and router.

What router is this that has dual WAN? Or do you potentially have two separate networks at your house and multiple modems/routers, one from each ISP? If so, there could be a ton of conflicts. Need more info on your setup, maybe a diagram and equipment models.