OpenVPN doesn't work after switching ISP (Asus router)

[whitenack]

Hey all,

I am limited in my networking ability so bear with me.

I set up a VPN between two machines at separate locations, using an ASUS router's included OpenVPN server software. I have managed to keep this working for several years, until the past couple of months when we switched ISPs. Now, I can't get my offsite machine to connect. One thing I have noticed is my ASUS router gives me the yellow exclamation mark, saying my IP address is invalid. I assume this is due to my DDNS settings being wrong now that I have a new ISP?

Any help would be appreciated.

 

[dave14305]

The Asus ddns (asuscomm.com) has been broken for a little while now due to a certificate issue, so that might explain the problem if you’re using a DDNS hostname in your VPN config. Or if you’re using a hard coded IP, it would have changed with the new ISP.

 

[whitenack]

Thanks Dave! Yes, I am using an asuscomm hostname. I guess I need to look for a solution to using asuscomm?

 

[RMerlin]

You can use a different DDNS provider. However if you get told you have an invalid IP it might be because the modem in front of that router is not bridged, so you are in a double NAT setup (or, the new ISP is using CGNAT instead of giving you a public IP address).

Check what the WAN IP address is. What are the first two numbers?

 

[whitenack]

I asked the ISP tech to put their modem/router in bridge mode, but you know how that goes.

I just created a no-ip account and tried again and it still isn't connecting. My router is showing my WAN IP is 192.168.x.x

 

[whitenack]

So I followed the suggestions here and am getting the same public IP address. So, if that is correct, my ISP modem/router isn't in bridge mode?

 

[RMerlin]

So I followed the suggestions here and am getting the same public IP address. So, if that is correct, my ISP modem/router isn't in bridge mode?

Correct. 192.168.x.y indicates that the modem is also acting as a router, firewalling anything in front of your Asus router.

 

[whitenack]

Thanks so much everyone! Got it fixed.

I poked around on the ISP router, found that it was in "IP Passthrough" mode, but noticed I had some other devices connected directly to the modem, in addition to the OpenVPN router. Looking at the ISP router documentation, it says that it only gives the first device the outside IP. So, I disconnected the other devices, just leaving the VPN router, and instantly got the corrected IP. From there, I just updated the client configuration to point toward the new no-IP DDNS, and got connected.

Thanks again, you guys are awesome!