Well it can't be your internet because you are here.
Look in your documents folder for Warband and find rgl_config.txt and see if "use_secure_connection = 1" and change to a 0.
If its already like that then either your firewall is blocking the game or there is an issue with your CD keys, I can't think of anything else.
You can go into regedit via search function and find "MountAndBladeWarbandKeys" and double check your CD keys are correct.
Just for confirmation your Warband is updated to 1.158 and Napoleonic wars to 1.104?