if this does not solve the problem - check the journal (ssh into the box and check for messages from 'pveproxy' in the output of `journalctl -b`) - and the pveproxy logs: /var/log/pveproxy/access.log
Thanks for the help. Finally got around to reinstalling proxmox. Web gui works fine this time around using https, so I'm guessing that was my problem the first time.