FritzBox 4040 Issues

Hi, I've switched to OpenWrt recently on my main router, FritzBox 4040 (I've used it for a good while on an ASUS-AC750 as a dumb AP and it's still working really well...) however I'm having some issues with it and the FritxBox 4040.
I followed the recommendations for this router here and here to set it up for better performance and reliability.
Recently though, I've had a couple strange issues.

  • A couple of weeks ago the router simply stopped giving DHCP to all of my Linux devices (PC, Laptop, Linux phone). I "fixed" that by resetting the router to factory settings using my android phone. Now this works fine.
  • Right now, my router gives DHCP to my android devices, but they warn "this network has no internet access" and the android phones only have LAN access but all of my Linux devices (wired and wireless) still have internet access.

As you can probably tell, this is quite frustrating and I'd like to know what I can do to fix this... or maybe it's a hardware/driver issue and I should instead look for a router with better OpenWrt support?

Let me know if you need logs/dmesg and sorry I'm kind of a noob with OpenWrt.

Thanks in advance!

Is usually a DNS issue, what DNSes are you using for your clients?

Yeah, I thought that at first, but that doesn't explain why the ethernet connected devices worked fine and my laptop over wifi.... the problem seemed to be android specific. I was using the ISP provided dns and changed it to google and cloudflare for testing but that didn't change anything.

Anyway, I factory reset the device and it seems to be working fine now until it breaks again...

are we even sure the devices use your DNSes ?

Most Android use DoT by default, and Chrome on Android have DoH enabled.

Seems to be fine for now, after a reset and using default ISP DNS.