Deluge
I am running Deluge and the WebUI on an ubuntu server at home. It is visible to the internet via an apache2 SSL enabled reverse proxy on the same machine.
Previously I was running this with my normal ISP router and I could access the WebUI fine through http://deluge.mydomain.tld
I put the password in the box when it pops up and it logs in fine.
However this morning I migrated my network onto a pfSense router and also changed the domain that pointed towards my webserver.
Now I can access the Deluge WebUI through http://bt.newdomain.tld but when I put the password in the box and click login, the password box immediately comes back up. There is no error and this happens perpetually. If I put a wrong (or no) password in, it warns me of incorrect password.
If I access the WebUI through the server name, eg. http://servername:8112 I can log in and everything works fine. It also works if I use localhost on the server.
The subdomain (bt.newdomain.tld) is mapped to the LAN IP in the pfSense DNS server otherwise odd stuff happens with the loopback and it doesn't work as I want it to. I have other services running through the reverse proxy which all have their own subdomains which are IP mapped to the LAN address and they all work fine. Everything also works fine from outside of my LAN, except the WebUI.