This does look more like an ssl error, but it is worth checking the following:
Check your /home/djangp-pbx/pbx/pbx/settings.py file. See what you have in the ALLOWED_HOSTS list.
It should look have in there:
'127.0.0.1', 'Your server IP', 'Your FQDN'
at the very least.
You can do a wildcard...