I run a Plex server, Sabnzbdplus, Sonarr, Watcher, Deluge and ZNC server on my Pihole device (an Intel NUC). After installing Pihole, none of the remote access web servers (excluding ZNC which seems to still work) are available to me. ZNC is on Port 5000, Plex -p 3200, SAB -p 5678, sonars -p 8989 etc. so they shouldn't be interfered with AFAIK.
Actual Behaviour:
Can't access any webservers outside or inside my LAN.
Accessing ZNC server does still work on LAN and WAN, so long as I use the DNS name. If I am within my LAN and use 192.168.x.xx:5000 then it does not load either.
You are not able to access them using just the IP address and port? Only port 80 is require for Pi-hole, and accessing directly via IP address does not go through Pi-hole, so it can't be affecting it.
Thanks Mcat12. I was having some serious PICNIC errors -- something to do with installing Pihole has made my Intel NUC crash (power off with no logs of overheating or anything useful in /var/log) which was actually why I kept not being able to access web servers. I have no idea why znc frontend was still being served, it must have been cached or something.
I have now installed Pihole on an old Odroid C1 running minimal Ubuntu 18.04 while I troubleshoot the NUC's hardware issue (or perhaps power supply?) and the C1 is blocking 700,000 domains like an absolute champ.