If you are able to host a server, it will show up on Master Server page: http://master.333networks.com/g/postal2
If you want to host a server, but nobody can join/see it, you can check the following:


Forward Ports UDP/TCP 7777-7788. Here are ports you need to forward:
game port: 7777/UDP
gsa port: 7787/UDP
master server port: 27900/TCP
query port: 7778/UDP

Here is an example for UT2004 game: http://portforward.com/english/applications/port_forwarding/Unreal_Tournament_2004/

Check your ports: http://canyouseeme.org/, Or check Master Server page (slow updates), or ask anyone join your server.








Network Priority change:
Try this: http://www.howtogeek.com/howto/27994/how-to-change-the-priority-of-wiredwireless-network-cards-in-windows/
Not help ? Try this: http://ecross.mvps.org/howto/change-network-connection-priority-in-windows-10.htm
If you wanna use hamachi - change adapter priority to high, active DHCP and change metric to 9000 or 10.
Helpful info: http://wiretuts.com/how-to-get-games-to-work-with-hamachi-on-windows-8/


Firewall settings change:
Disable Firewall: http://www.wikihow.com/Turn-off-Firewall
Open Firewall ports: http://www.dummies.com/how-to/content/how-to-open-a-port-in-the-windows-7-firewall.html


We hope this help you to setting up your router/network.
All hosting/connecting playing work in 100%. We played more than 300 hours of tests and know that it works, all other problem only on your router side.
Have fun! Guns don't kill people, you do. (only a fiction people... ofc)


This error happens because you and host player have different versions of game files. Like diffirent mods/textures packs or you installed any localisation.
You have to use same version of game and mods as the HOST player. Different packages not available in Online coop!
SOLUTION: delete unmatched files and press check files in steam for POSTAL2.


Linux Solution:
Just change your "~/.lgp/postal2/System/Postal2.ini" with this: https://gist.github.com/Koncord/5ea0d1daec8f1c6185eb72d4ad09eca0


MAC Solution:
backup your postal2.ini
replace it with postal2CoOp.ini (just rename it to postal2.ini)
launch P2 via shortcut or steam