For netstat it shows no port 8333 open.
tcp 0 0 localhost:6379 0.0.0.0:* LISTEN 14879/redis-server
tcp 0 0 localhost:8332 0.0.0.0:* LISTEN 27202/./omnicored
tcp 0 0 0.0.0.0:http 0.0.0.0:* LISTEN 7236/nginx: master
tcp 0 0 localhost:postgresql 0.0.0.0:* LISTEN 7955/postgres
tcp 0 0 0.0.0.0:smtp 0.0.0.0:* LISTEN 23875/master
tcp 0 0 0.0.0.0:https 0.0.0.0:* LISTEN 7236/nginx: master
tcp 0 0 localhost:24444 0.0.0.0:* LISTEN 826/NBXplorer
tcp 0 0 localhost:1088 0.0.0.0:* LISTEN 4989/uwsgi
tcp 0 0 localhost:1091 0.0.0.0:* LISTEN 5059/python
While there is nowhere that shows that BTCPay and Omni cannot work on the same server, I have seen it suggested that since Omni is essentially running bitcoind you should not need a separate server if you need bitcoind's features.
Do you have something like this in the omni conf file?
rpcpassword=your very secure password
rpcport=8333
rpcallowip=127.0.0.1
According to this:
https://github.com/OmniLayer/omnicore/blob/master/src/omnicore/doc/rpc-api.md
8332 is the default port for omnicore so you will have to set it in the conf file to be 8333. It looks like you did not do that. If you *did* then for some reason it's not reading the conf file.
So I would start poking around there. Set it to some really odd port and run netstat and see if it shows up there,
Other then that I have no idea.
-Dave