I’m using a dual-wan router and I constantly have problems trying to post. Every time I click the submit button I get logged out. Can you please turn off the IP check of the forum if that is the problem?
I am afraid that phpbb does not include this configuration option and ever checks the IP during the authentication process. I should hack the PHP code, but I am very busy. When I tested the load balancing features of Zeroshell also had the same problems, but Zeroshell allows to set manual balancing rules. In that case I just had to say to Zeroshell to use the same link if the destination IP is the IP of http://www.zeroshell.net and the destination tcp port is the port 80.
Could you do the same think with your WAN router?