I’ve recently suddenly had issues with DNS lookups failing to resolve.
Adventure with ISP / rant
After verifying the problem wasn’t on my end, I eventually called my ISP. However, they didn’t really understand the issue. After speaking to 9 other people and being assured my DNS queries for some domains were failing because my Wi-Fi signal was bad (I was using a wired connection), I eventually reached someone from the technical department. They told me that questions regarding DNS were too technically complex (???) and told me to check their forums instead. There I found someone that knew what was going on, and apparently my ISP had recently started enforcing DNS rebind protection without the ability to add exceptions. There was no option to disable or work around it it with the ISP’s modem, and the only option was to use your own router or configure a hosts file on each device.
I have flashed an old access point with OpenWRT and have started using that. It has helped me to get any access to my selfhosted services (without manually setting it in the hosts file that is) but still occasionally randomly fails.
- Migrated all devices to the OpenWRT network
- Changed the public DNS record to use a CNAME record which points to my router’s local device alias
- Exempted DNS rebind protection for my domains in the OpenWRT settings
Since it seems to happen at an odd interval and the records have a 5m TTL, I suspect DNS records might be expiring from the local cache and getting a response from a different upstream DNS server in the pool, but that’s just speculation. Does anyone know what could cause this issue?
Have you tried tracing the issue? What is uptimekuma using for DNS? What do the logs on that server show?