Connection issues on Archer A6 v3

I am using OpenWrt 21.02.3 r16554-1d4dea6d4f with a new Archer A6 v3 router. There wasn't much configuration I did after flashing, beyond passphrases and setting a static lease for my server. I am experiencing some odd issues, and I'm not sure if they are symptoms of the same problem or two separate problems.

  1. The network occasionally goes down.
  2. My server has trouble acquiring a DHCP lease.

Re 1: This happens sporadically, and I don't know yet if it's totally random or if there's a trigger. I've seen it happen both during heavy usage (middle of workday) and hardly any (middle of night). Sometimes it goes for hours without problem, other times it dies again after a few minutes. The symptom is that the network suddenly stops working, and the router only has the power LED lighting up. Since neither LAN nor Wifi works in that state I can't do any diagnostics, but after turning it off and on again the network works normally. Checking the syslog, I have not noticed any obvious error messages.

Re 2: The server in question is connected by Ethernet and uses NetworkManager. In NM I have IPv4 set to auto and IPv6 set to disabled. I also tried others (Disabled, Ignore, etc) to no avail. The router is configured to assign a static IP to this machine. What I expect to happen is for the server to naively ask for a DHCP lease, and always ending up with the correct IP that I want. Instead it times out waiting for DHCP. Occasionally it will connect and work, and then stop working again (often after problem 1). I'm not sure what makes it work vs. not, it seems sporadic and I haven't noticed any patterns. By the way, my other PC is able to connect via Ethernet & DHCP without problem, although there's no static lease set up for it.

How do I go about determining if these are related, and also finding out more information about what the problem(s) are?

fwiw, unless you have a serial connection to permanently monitor/capture all messages, it may be difficult to diagnose router dying issues. Someone else may be able to offer another suggestion.

As most issues tend to be wireless related, have you considered disabling wireless to see if the router is more stable?

Regarding the DHCP issue, have you examined the openwrt router's System log?

Do you see DHCPDISCOVER, DHCPOFFER, DHCPREQUEST and DHCPACK messages from your server?

If you reduce the DHCP lease time to say 4 minutes, the client (your server) should be request to renew the lease every 2 minutes (at 50% of total lease time) in theory.

If this new router is still in the warranty period, flash back to stock and test for a few days with stock firmware. If it still crashes, get a warranty replacement. Even if it isn't under warranty, testing with stock firmware is a good way to confirm a hardware problem.

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Well, I've fiddled with it a bit and made some progress.

I deleted the static lease for my server in OpenWRT. However, there is still a domain mapped to the server's expected IP, (Network / DHCP and DNS / General Settings / Addresses).

I then set NM on the server to Automatic IPv4 and disabled IPv6. The server was able to connect, could ping, and other machines could ping the server. Of course I do need this server to always stay on the same IP, so I thought that deleting the static lease would cause a problem there.

To check, I set dhcp.lan.leasetime='4m'. Even after this, the server still keeps connecting at, despite me deleting the static lease.

So does this mean that I can just leave things as they are, and the server will stay on .100 in the future?

The MT7613BE radio is a known problem child, unfortunately. I've been told things should have improved with 22.03. Could you try RC5 on it? Make a backup of your configuration before upgrading, but you should be able to upgrade without needing to wipe your settings.

Stock firmware will (still) probably be more stable on this device, unfortunately. So like @mk24 suggested, if you're still within the warranty period, I'd restore stock and return it and get something with better supported wireless if possible (MT7615 e.g.).

No guarantees the server will keep the .100 address indefinitely.

If the openwrt router is rebooted, I believe it will have no record of assigning .100 to your server. Your server may be asking the Openwrt dhcp server if it can have .100 address provided it is not already been allocated to another device.

Did you inspect the system log for DHCP messages ?