Intermittent failure to receive replies

#1

Expected Behaviour:

Normal, uninterrupted operation after updating FTL from 4.2.2(iirc) to 4.2.3

Actual Behaviour:

After the FTL update, initially once a week or so, but with slowly increasing frequency, DNS resolution seems to stop working. When checking the tail log, I can see requests being received and sent along, but no replies at all. Occasionally this will resolve itself after a few minutes, but sometimes restarting the DNS service or the entire system is needed to resolve the issue. As a side effect, I’ve had to restart before generating the debug token, if that matters.

Debug Token:

https://tricorder.pi-hole.net/11s0zos8k4!

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#2

This is very strange, do you experience the same issues when you (temporarily) try another DNS upstream server like Google’s? Also, is the issue immediately resolved after restarting the DNS service (I guess you’re restarting the process pihole-FTL) or can the issue be connect to intermittent Internet connection issues on you or the DNS provider’s side?

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#3

I’ve got one OpenDNS (208.67.220.220) and one DNS.WATCH (84.200.69.80). I haven’t tried swapping the upstream servers, but I will next time it happens. I’ve been restarting the DNS resolver and the system using the web interface buttons in settings. I try restarting DNS resolution first, which immediately fixes it ~70% of the time. If that doesn’t do it, restarting the system does immediately fix it once the system boots back up. I initially thought to check the pihole because I couldn’t ping google.com, but could ping 8.8.8.8. I do occasionally have intermittent internet issues, but when that happens nothing gets through at all, and windows gripes at me.

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#4

Finally had it happen again. I did verify I could ping out by IP address, but not by URL. Didn’t restart this time. Ran debug, but it rather predictably didn’t upload. Here’s a screenshot of the tail log as it was happening.

Once again it fixed itself after a few minutes on its own, before I had time to try switching upstream servers.

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