I have recently resurrected a Windows 7 computer with the intent of hosting an ArmA III server on it from home (using TADST). What I have discovered with my Billion router is, when you set up port forwarding for ArmA III and Steam; ensure the desktop computer hosting the ArmA III server has a static IP address configured under the DHCP Server settings of your router.
My issue was the IP address for my desktop computer hosting the ArmA III server was leased in DHCP and thus when it expired (every 24hrs) the IP address changed. This caused the IP address of the desktop computer hosting the ArmA III server to be different to the router port forwarding rules I previously created (thus why I could not see the server session being hosted on the Internet from my gaming PC).
Once I assigned the desktop computer hosting the server an internal static IP address (via DHCP Server options) and setup the port forwarding rules to mirror this IP on the router, it was consistently displaying the hosted server on my gaming PC Internet browsing function.
Router Port Settings
TCP/UDP: 2302-2305
*Note* I use TCP also, as its seems to affect the ArmA III Squad XML tags if its UDP only (ie./ they didn't appear for me when joining the server mission)
TADST Port Settings
Port: 2302
Steam: 2303
Procedure I use for best results:
-Start up ArmA III hosted server using TADST
-Start up Game and select PLAY > MP > Internet and refresh server listing straight away (once I have done this it can take between 10-30 seconds for the server to appear in the listing (server name filtered).
-If it it does not show, restart game on your gaming PC and try again.
-If its still not there, restart router and try process again
The only issue I have now is getting subscribed Steam workshop missions on the PC which hosts the ArmA III server, to show in the MP Missions listing when I connect to it via my gaming PC (on a normal PC they will be in orange font, however don't see them when I connect to the server box). BIS Feedback Tracker ticket has been lodged :)
cheers and beers (thanks Tophe for a great utility)