Same problem here! It cost me 2 days of error searching until I found this topic here that the problem is the firmware. Port Forwarding and Dyndns are not working for MR3420!!!

Region : Austria Model : TL-MR3420 Hardware Version : V2 Firmware Version : TL-MR3420_V2_121206 ISP : 3 Hi, I am using a MR3420 V2 together with a E398 modem. The connection works well, but I can't...