x86 Generic No network after suspend

Just started to get a similar issue with my stable 12.0.1 Generic-Legacy, but it's not tied to the system suspending but just the NIC to stop functioning randomly. The fix is to restart the system.

In the settings it shows that it doesn't get an IP from the router while all other systems have no issue at all, even tried to swap the LAN ports on the router side, but that doesn't help either.

Unplugging the Ethernet cable and replugging it also doesn't do anything.

The router itself on the other hand shows that the system is present, active and has an IP associated with it (it's set to always get the same IP).

The system is fully unchanged using the 12.0.1 Generic-Legacy that was released in August last year, and it started happening yesterday. No add-on updates or anything, it just started.

I'll try the mentioned nightly build in hopes that fixes it. If anyone has other ideas, I'm all ears (and yes, I also tried several other Ethernet cables).

Little update:

A weekend with debug logging enabled later, to catch what might cause this, it didn't happen all weekend. I turned off debug logging and sure enough, 30 minutes later it happened again. But I still got some insight/info whats happening.

From the logging in my router, it seems to happen when the system is renewing the DHCP lease. It happened 2:44am according to the system's time, and the router reports the last IP/DHCP activity for the system to be 2:44am as well.

Unplugging the Ethernet cable to "reset" everything at first does nothing, but deactivating cable networks, unplugging the Ethernet cable, exiting back to main menu, going back to enabling cable networks and then replugging the Ethernet cable finally gets it to regain a usable connection. And I suspect it will stay that way until I reboot again.

Still haven't tried the mentioned nightly yet, but will do that soon. Although, I'm not ruling out a hardware fault at this point, because the system is pretty old by now (about 10 years, it's an AM1 AMD Athlon 5350 system) so the board might be on its way out (the HDMI port is already starting to have issues when the plug is not in a certain position). Luckily, I got the exact same board as a spare that only ran maybe 2 years, so I'll test that too in case the nightly doesn't help.

Little update:

Had time to test around a few things, among them were several nightly builds. Nothing fixed the issue.

Then I tried to remember if I had changed anything on the home network side before it started and yes, there was something I changed, I activated IPv6, in a 6to4 tunnel, and DNS over TLS.

Reverting the DNS over TLS didn't help, deactivating IPv6 in my router seems to fix it, at least I haven't had the issue at all in the past 7 days.

I'll update if necessary, because I have a hard time believing that libreelec has issues with IPv6 (6to4).