ok, DNSSEC is disabled and i will not enable it again since the problem is solved...
I can confirm the described problem. Same setup:
-> Fritzbox 7590 as router and only uptream resolver
-> conditional forwarding on
-> DNSSEC on
I have disabled DNSSEC and conditional forwarding now. At the moment, system is stable.
Of course! We aim to fix anything. However, one of the two has to be true:
- I can reproduce the issue: Fixing it is much easier.
- I cannot reproduce it: Oh well ... then the way down to finding what is really happening can be long.
Two days and the system is stable with DNSSEC disabled (need conditional forwarding for the Top List naming), think DNSSEC is the source of the problem in a setting with FRITZ!Box as Router and Upstream DNS! For me the problem is solved, thanks!