I just bought an Archer BE800. I love the features and speed when it works, but I've been fighting issues every day trying to get basic things to work. It is connected to a Motorola MB8611 cable modem on Xfinity.

I have the latest released firmware:

Firmware Version:1.1.6 Build 20240808 rel.26673(5553)

Hardware Version:Archer BE800 v1.0

My first problem which now seems to be resolved was my wired internet speeds were very low, like 20-40 mpbs (my service is 1Gbps speed), but I got almost 1GBs on wifi. This seems to have been resolved by in the Network->Internet tab of the web interface, by changing the "Internet Port Negotiation Speed Setting" from Auto Negotiation to 1000Mbps Full Duplex temporarily but then changing it back to Auto Negotiation.

However, my current problem is that I seem to lose all internet connectivity several times a day and the router shows the ! on the LEDs. Both wired and wireless lose internet access. My wifi networks are still there, but just have no internet access. After a few minutes it comes back up on its own.

So it seems like there is a problem between the WAN port (I'm on port 1 of the combo port) and my cable modem. I've used the same modem for years with zero problems until I replaced my really old Asus wifi router with the BE800.

I tried changing the Internet Port Negotiation Speed Setting" from Auto Negotiation and left it at 1000Mbps Full Duplex since my last router was only 1Gbps. Since I made that change it seems to be better, but did still happen once today. I'll keep it like this for a while to see if it helps.

I've done all the standard troubleshooting such as power cycling everything many times. I've tried multiple ethernet cables including the cat5e that I used for years with my old router and the cat6a that came with the BE800.

I think the problem is probably the BE800 since it started when I got it, but acknowledge that it could be the cable modem as well but have had no problem with the modem for years.

How can I diagnose if the BE800 or the cable modem is the problem?

Do you have any suggestions on how to get this most basic of functionality to work?

Thanks.