I'll give the fix a try in the next few days!
In the meantime, I also discovered something strange. I noticed that I have many unbound-control processes running on my router:
# ps | grep unbound-control
2335 root 5988 S /usr/sbin/unbound-control -c /var/lib/unbound/unbound.conf local_datas_remove
2385 root 5988 S /usr/sbin/unbound-control -c /var/lib/unbound/unbound.conf local_datas
2428 root 5988 S /usr/sbin/unbound-control -c /var/lib/unbound/unbound.conf local_datas
2995 root 5988 S /usr/sbin/unbound-control -c /var/lib/unbound/unbound.conf local_datas
3839 root 5988 S unbound-control -c /var/lib/unbound/unbound.conf stats_noreset
3970 root 5988 S unbound-control -c /var/lib/unbound/unbound.conf stats_noreset
4090 root 5988 S unbound-control -c /var/lib/unbound/unbound.conf stats_noreset
25060 root 5964 S /usr/sbin/unbound-control -c /var/lib/unbound/unbound.conf local_datas_remove
25064 root 5964 S /usr/sbin/unbound-control -c /var/lib/unbound/unbound.conf local_datas_remove
28771 root 5984 S /usr/sbin/unbound-control -c /var/lib/unbound/unbound.conf local_datas_remove
29845 root 5984 S /usr/sbin/unbound-control -c /var/lib/unbound/unbound.conf local_datas_remove
30351 root 5984 S /usr/sbin/unbound-control -c /var/lib/unbound/unbound.conf local_datas
30681 root 5968 S /usr/sbin/unbound-control -c /var/lib/unbound/unbound.conf local_datas_remove
30721 root 5968 S /usr/sbin/unbound-control -c /var/lib/unbound/unbound.conf local_datas
And they seem to be stuck somehow. If I manually try to execute unbound-control, it also doesn't return:
# unbound-control list_local_zones
At this point dns resolving is also problematic:
$ dig aaaa google.es @192.168.1.1
; <<>> DiG 9.16.1-Ubuntu <<>> aaaa google.es @192.168.1.1
;; global options: +cmd
;; connection timed out; no servers could be reached
$ dig aaaa google.es @fd81:631b:716f:10::1
; <<>> DiG 9.16.1-Ubuntu <<>> aaaa google.es @fd81:631b:716f:10::1
;; global options: +cmd
;; connection timed out; no servers could be reached
When I kill all those processes, everything starts working again.