SIP blocked on ASUS DSL-AC68U - anyone got this working OK?

[astenglian]

Hello SNBers

I have been using SIP via a Siemens C475IP box for years via various broadband providers and various routers. I've even taken the box on holiday and weekends away and plugged it in and it's always worked.

I recently moved to FTTC broadband on Plusnet. Using their Plusnet One router (equivalent to the BT Homehub 5) everything worked fine. However, my DSL-AC68U blocks SIP traffic. I have read various threads on this site and can see a whole bunch of suggestions, none of which seemed to work for me. My setup has just the one router/wireless box and the VoIP/SIP box is connected to that directly and uses a fixed IP.

As I'm using the DSL version of the AC68U that is a combined vDSL modem and router rather than the router-only RT-AC68U version, I can't move to the Merlin firmware.

Is there anyone using standard ASUS firmware who has successfully configured the box to work with SIP traffic? If so, what is your configuration?

Thank you.

 

[astenglian]

OK, I worked it out. After reading a bit more and stepping through the various config options more methodically (it was very late last time) I have got it to work. The set up was:

- UPnP = OFF
- UDP port forwarding of 5060 to the Gigaset box

I could set SIP ALG (call "SIP Passthrough" in the ASUS UI) to either enabled or disabled and both worked. I toggled each of these settings independently and cycled the SIP connections. It was only when it was configured like this that the SIP services registered.

Btw, the Gigaset box had local/listen ports set to SIP=5060 and RTP=5004 - 5020, which are the default settings. The STUN setting was OFF.

I should also add I am on Firmware Version:3.0.0.4.380_7361

 

[Deepcuts]

I think the problem is double NAT
I have been using AC68U for quite some time with VoIP without any issues, but no double NAT.

 

[astenglian]

I think the problem is double NAT
I have been using AC68U for quite some time with VoIP without any issues, but no double NAT.

Thanks, Deepcuts. I did get it working and posted my fix above. Tell me more about double NAT...? From what you've said, I think you've turned this off. If so, can you tell me how?

 

[Deepcuts]

Double NAT: when you have two routers, both using NAT and a local network behind the 2nd router.
This kind of setup can cause serious problems.
Either only use the router from your ISP, or ask your ISP to put their router in bridge mode and keep the Asus one doing the NAT part.