SIP register unsuccessfull

Michal

Hi,
I have some trouble with SBG3600 which have two WAN interfaces in use (LTE and ETH). I set forwarding policy - all traffic from my SIP server (3CX if it's relevant) goes through ETH WAN. It works for most of the time but sometimes all SIP trunks unregister. I still have www access from this server but PBX don't receive any reply from service provider. 
All I need to do is go to router management > Broadband open Edit window and without doing any changes click Apply. After a while all trunks are registered. I didn't have this sort of problem on my previous router.
How to solve it or debug this issue? 

Best regards

Jeremylin

Your SIP server is on the Lan side,right?  In my office, I also place the SIP server, but SIP server is on SBG's wan side not lan side. It's working fine. Just curious what NAT rules and forwarding policy did you set.

Michal

Hi,

check attached pictures

even if WAN interface is called DSL it's ethernet (there is obligatory modem from service provider set in bridge mode). 

Regards

Zyxel_Charlie

Hello Michal,
Please capture the packets from both WAN and LAN interface when the issue is happening. I want to see what may go wrong by analyzing the packet.
Here I show you the procedure so that you can capture packets from the device directly.
https://businessforum.zyxel.com/discussion/731/how-can-captured-packets-be-save-as-wireshark-compatible-files-via-tcpdump-command-in-the-sbg3300#latest
Charlie