I am having a strange problem with the port forwarding of my tomato router. Tomato 1.27vpn3.6 running on buffalo WHR-HP-G54. I am running Sipsorcery server on my local PC on 10.10.10.15. I set up a port forwarding rule to forward all SIP traffic to port 5060 of my router's WAN IP address to this pc. The rule is as this: On, Both (TCP and UDP), src addr blank, ext port 5060, int port blank, int addr 10.10.10.15, For some reason, I needed to have my ATA located on the same LAN to register to this server through the WAN ip address, as if the router is between the ATA and the server. The ATA uses port 5061, ip address is 10.10.10.11. I used the dyndns host name as the sip proxy. From wireshark, I can see the sip request is sent from 10.10.10.11/5061 to w.a.n.ip/5060, and then forwarded packet as from w.a.n.ip/5061 to 10.10.10.15/5060. This is exactly what I wanted. I have this setup for 3 months now and it works great. Now, I need to do the same thing for another ATA, at 10.10.10.12. I simply set up the ATA2 to use port 5063, and use the same dyndns host name as sip proxy. However, this time, the sip request packet is not forwarded. I can only see the packet from 10.10.10.12/5063 to w.a.n.ip/5060, but no forwarded packet afterwards, the ATA just keeps sending the request until it times out. Since I set it up to make to first ATA work more than three months ago, I really cannot remember if there is anything else that I need to configure to make this forwarding work. But as it is now, it is very strange that this rule only work for one ATA but not for the other. anything I missed? Please help if you have any suggestions. Thanks.