Weird setup at in-laws, with weird symptoms

[JaimeZX]

Bought an AC-RT86U for the in-laws. Put Diversion & Skynet on it at my house before bringing it here, to save time.

NOW. I get here, duplicate their old router's SSID and password so everything should be seamless for them.
But it ain't.

They have Comcast, and get their home phone number through Comcast, so they have this little Linksys VOIP adapter for their normal land-line. Their old router was also plugged into this Linksys VOIP adapter (SPA2102-R. On the label it says "Phone adapter with router.")

SO.
There is a big-@$$ Comcast modem/wifi-router that plugs into the Linksys VOIP-router that plugs into the old Netgear router. Three routers.

The Linksys VOIP offers 192.168.7.3 to the "big" router. The old Netgear works fine here. But if I simply swap the Cat6 from the old Netgear to the new Asus, things fall apart some. The Asus accepts 192.168.7.3 as its WAN IP. If I SSH into the Asus, I can Ping Google, I can download & update all the scripts. But any clients connected to the Asus have no internet. The Asus GUI shows Internet is "Connected."

Suspicious that this triple-router setup is to blame, I try bypassing the Linksys and plugging the Asus directly into the Comcast. But then Asus tells me "Your ISP's DHCP does not function properly." So I'm thinking maybe they have a static IP for their phone?

How would y'all troubleshoot this? I've never experienced the router having internet but none of the clients before...

 

[L&LD]

Power down the entire network infrastructure. Wait for at least 15 to 20 minutes (1 hour or more is ideal) before powering anything back up again.

Power it back up starting with the modem/ONT, first router, second router, third router.

Wait at least 5 minutes before powering on the next router.

HTH.

 

[JaimeZX]

WELL. I tried that and it didn't work. Since it was bedtime, I powered it all down and went to bed.

When I got up I started the Comcast modem/router and made coffee.
I drank some coffee.
I started the Linksys VOIP adapter/router and drank some coffee.
Went out to look at their garden.
Came inside, booted Asus. Drank some more coffee. Talked to my boy.
Looked at my phone. I saw the "wifi connected" icon with a little X on it, indicating no connectivity.

Lots of pinging. I could ping any IP address from the router or a connected host, but there was no name resolution at either. So... DNS issue?

I went back into the Asus GUI and saw that DNS-over-TLS was set to "Strict" but there were no servers selected. So... lol I added some servers and all seems to be fine. Guessing it was working when plugged into the old Netgear because somehow the Netgear was providing the name resolution? I don't really get how that's possible given the above settings, but I think we're G2G at this point.

Thanks for the assistance!!

 

[ApexRon]

The ASUS and NetGear are both assigned an IP address of 192.168.7.3 . I am thinking of these possibilities:

1. Where it my install I would use NAT on the ASUS as well. Yes, double NATing. Downstream network of perhaps 192.168.8.0 .
2. Default gateway issue? Check a device on WiFi and see what the default gateway is.
3. DNS server issue? Check a device on WiFi and see what DNS server is assigned.

 

[dosborne]

I think we're G2G at this point.

Although the issue is reported to be fine at this point, and hopefully someone will correct me if I am wrong,......

But, to make things easier at some point in the future if you are messing around with things again, you may not have to introduce the VOIP box between the 2 routers. I have a similar setup with different brands from theirs. I start with my ISP router, then plug my VOIP box into one port of that, then plug my ASUS router into another port. This allows the VOIP ATA box essentially direct access to the internet and avoids running all my network traffic through it (not sure what the overhead of that it what kind of switching it does....just want to bypass it). Now, I run double NAT so not sure if that is a requirement in this scenario or not. The alternative would be to run ISP router/modem -> ASUS modem -> VOIP box

Either way, and again I have nothing to back this up, but I would avoid running all my traffic through the VOIP box.

 

[JaimeZX]

Yeah, I would like to do that but the Comcast modem password is not what I set it to a few years ago, so I assume Comcast went in and did something. I'll be back here in a few weeks and continue investigating.

On the plus side, if the VOIP means they have a static IP that'll save me effort when I set up their OpenVPN server...

 

[dosborne]

A static IP is not a requirement for VOIP. At least in my case, the ATA box connects to the VOIP server and registers itself.