Here is the link to the manual for your DG834G:
Here is a link on ADSLgeek about it:
I don't know anything about your third-party firmware, but most of the consumer CPE practically configures itself. I've configured my DSL router to allow web requests to one internal Linux box, and now the whole world attacks it 24/7! Standard NAT with port forwarding should allow you to publish a web site on one box, SSH in to another, etc., and you should see the IP addresses of the attackers in /var/log/secure, /var/log/audit/audit.log, and the Apache logs.