Pihole inaccessible - running on Synology VM

Not sure what's going on but my Pihole has randomly stopped working twice in the last couple of days - only change has been enabling IPv6 on my ISP router. As of this morning was running fully up-to-date.

Your debug token is: https://tricorder.pi-hole.net/2S9etq3n/

Could you check your /var/log/pihole/FTL.log file once it happens if there is anything abnormal showing up?

Thanks, will do.