DD-WRT: How to allow port forwarding to apply to requests originating from inside the LAN? - Super User

router - DD-WRT: How to allow port forwarding to apply to requests originating from inside the LAN? - Super User

Try disabling "Filter WAN NAT redirection" in the Security->Firewall tab. From the help description:

Filter WAN NAT Redirection Prevents hosts on LAN from using WAN address of router to contact servers on the LAN (which have been configured using port redirection).