First, be sure you are connected with the OpenVPN protocol, rather than IPsec. (Open the app settings [three lines on the top left of the screen], tap Settings, then tap Protocol. From there, select OpenVPN.)
Then, use the following instructions to change ports:
1. Go to your Settings
2. Go to Socket and select UDP
3. Tap the Remote port option.
4. Try changing the remote port to 1194, and try connecting.
5. If that does not work, change the port to 9201, and try connecting.
6. If that does not work, change the port to 8080, and try connecting.
7. If that does not work, change the ports to 53, and try again.
8. If none of those work, enable a TCP connection by going back to Settings, then Socket, and selecting TCP
9. Try connecting to remote port 443.
10. If that does not work, try 110.
11. If that does not work, try port 80.