For safety for all paradox games i open 2300-2400 (it was written for eu2), 28000-29000 (hoi2 manual), 47400-47700. Yes, it works good with any pdox games.
You can order external IP from your provider, and then if you receive directly, it should work (if through router, you need to set port forwarding at router). I never tried, but it should work to connect, though the ping is never stable.
New LTE provides really stable ping (tested in World of Tanks), so should be playable.
So to play pdox games you have to have:
1. External IP
2. Port forwarding at your router
3. All firewalls off or definetely made proper exceptions
If you don't have, use hamachi (
www.hamachi.cc)
Gameranger was not stable much, when we tried it - comparing hamachi
We tried one more client- tangle - it was unstable as well - connection was dropped out after some time.
With hamachi you should have green lights to server and to all (no blue, yellow or orange), and best if to all players. If your connection is under many routers or weird routers or HSDPA etc sometimes you have only blue - limitted connection, and you will drop the game after several minutes for sure.
If any player is using hamachi in game, all should use hamachi, even if connection by external ip to server - that avoid to have misconfiguration between players (in eu2 it meant like i see zero armies, while there can be several thousands troops). Also at Hamachi they recently limitted (free?) group to 7-8 users instead of 17 before - that makes problems for mp game to have several hamachi groups for intercrossing of users.
But the best solution is still same as written before - buy external ip, configure your router, firewall offs. Sometimes you can think the problem is not your end, but after all the problems are only these three rules.