VOIP Tech Chat → [Other] Baffled! Grandstream HT-502 behind router doesn't work

I have been having difficulty getting a Grandstream HT-502 running behind my firewall.

History (long, but I expect helpful):

1) I originally started using a HT-486, and everything worked fine. I started with a reset configuration, added callcentric account specifics, set for NAT periodic punchthrough and WAN side HTTP access. My router correctly shows the ATA as being registered. The only problem keeping me from joy was I learned the HT-486 does not offer a flexible dialing plan. SO - I ordered an HT-502.

2) HT-502: I started with a reset configuration, and essentially performed the same configuration changes as for the HT-486 - callcentric stuff, WAN access, and NAT keepalive. The HT-502 successfully registers if I put it before the firewall (but then I can't get my router to run the rest of my system), but when I put it behind the firewall, it does not work. I note that the router does not seem to acknowledge that is exists (green lights, but does not show it as being assigned an IP address, etc) - although the HT-502 (as queried from the LAN side when I manually patch my PC there) shows a "reasonable" WAN address. And yes, I did enable Line 1, and disable line 2. Note that at any time, if I replace the HT-502 with the HT-486, it registers, and works fine.

3) Everything is set using DHCP, which is default. I am fixing no IP addresses, etc.

What am I doing wrong with the HT-502??

Here are the summary combinations that work and don't work:

A. HT-486, behind router - works
B. HT-512, behind router - does not work
C. HT-512, in front of router (i.e. router attached to LAN port, cable modem attached to WAN port) - works (registers with callcentric, etc), although then the rest of my system behind the router does not work (I am not doing anything with DMZ, etc - don't really know how to make that work).

I would be happy with solutions placing the HT-512 on either side of the router.

Any help is appreciated!!

Chuck

What router are you using? I set my 502 behind my Linksys WRT54G running Tomato with a static IP address of 192.168.1.130, not ports forwarded.

I am at work now, will check when I get home. I know it is a US Robotics 4 port (+ wireless) NAT router. I currently have not set a fixed IP address (never tried it before) - usually the address that gets handed out is 192.168.2.X, where X is 3, 4, 5 or 6. This (automatic assignment) works with the 486, but the 502 - well, something seems messed up - the 502 says it has, say 192.168.2.4, but when I go to the router config screen, it doesn't show it as even being in the system (unlike when the 486 is connected)...

Am I making sense?

I can see a couple of ways to attack this problem:

1. Double-check the 502 to make sure it really is set to acquire an address via DHCP. Check that the router has enough addresses available so that it can assign one to the 502. Check that the router is set to assign addresses via DHCP. (I know, you've done all that. But the router is acting as if it has not assigned an address to the 502 via DHCP.)

If that doesn't make a difference:

2. Put the 502 in the router's DMZ. In other words, tell the router that all packets not specifically destined for another local network device should be sent to the 502. To do this, assign a static address to the 502. This address must be outside of the range of addresses that the router is free to assign via DHCP. Tell the 502 not to acquire an address via DHCP. Then find the DMZ settings in the router. The router should have a place where you can set the IP address of the DMZ device. Set the 502's IP address in that place.

I am using a US Robotics wireless MaxG router, running whatever default software that comes with. My setup is pretty normal, out of the box, although I do punch 2 holes and port forward to one of my computers. DHCP pretty much everywhere. I don't really know how to set up static IP addresses - am I correct that you either do it to everything, or use DHCP, that you can't mix these? As occasionally we have wireless PCs come to join us, I don't want to force them into setting static IP addresses, etc.

Hope this limited amount of information helps. On the bottom of this post I will try to post some screen shots that all can see....

Thanks,
Chuck

For those who are interested, here are some screen shots of my 502 configuration (when behind the router, not working), my router status pages (when used with the 502). Also I have included a screen shot of the router when my working 486 is attached behind the router. Can anyone spot the problem?

Also, I tested it again - if I attach the 502 to the cable modem directly, it works fine. Strangely, though, I can connect my PC to its LAN port and surf freely. However, if instead I connect my router, none of the connected computers can access the internet at all (fixed, when I finally give up and connect the router, without configuration to the LAN). STrange.

I welcome any insight!
Thanks
Chuck

No. You can designate a range of addresses for the DHCP server to assign dynamically, and then statically assign other addresses outside that range. The DHCP server speaks only when spoken to. It has no interest in addresses that are outside its range.

Set the 502 up as a bridge or give it a different lan address on its router not the usrobotics.

they cant both exist on the same wan and lan.

Your 502 is getting an address in the same subnet as is in its internal lan. That wont work. Give its lan something like 172.16.15.1 and things shoul start working.