OpenVPN issues

[Sabbath81]

Hello Guys,
i have a very strange problem connecting to openvpn on my asus ax88u.

in the local network, the connection works, but if i go to mobile / other wifi , it does not connect.

May you advise?

Firmware:3004.388.4

i cannot access ddns from outside home network as well

 

[ColinTaylor]

See the error message in orange at the top of your screenshot. Your RT-AX88U does not have a public IP address.

You appear to be behind another router device. You need to forward UDP port 1194 from this "other" router to the RT-AX88U's WAN IP address.

 

[Sabbath81]

Thanks, i will call the ISP, as obviously this is the reason.

Is this causing the ddns being inaccessible from outside?

 

[Sabbath81]

Thanks, i will call the ISP, as obviously this is the reason.

Is this causing the ddns being inaccessible from outside?

So the ISP reports that they changes the addressing from static to dynamic.

I am not quite sure why this reflects vpn connection when using ddns.?

 

[Ripshod]

Is your router connected to an ISP modem/Router? Could you get that device set into bridge mode? Or better still remove that device from your setup?
If you can access the isp device it's possible to either port forward to your router, or put your router into it's DMZ.

 

[GSpock]

Presumably, your AX88U WAN port is connected to a LAN port of your ISP modem/router.
Is your ISP modem/router is configured in bridge mode ? If it is, then your AX88U must have a public IP address and you should be able to access via DDNS (check again if the yellow message is this there on the OpenVPN Server page); If not, then you need to do what wrote @ColinTaylor above (port foward) and make sure your DDNS gets the public IP from your ISP modem/router

 

[Sabbath81]

Hello guys,
i dont have any other device than my AX88 at home. So the ISP connects directly to the WAN port of the Asus. the ISP said that they did not close any ports. I am totally confused why the DDNS is not accessible from outside the home network.

 

[Ripshod]

Would make sense to change the "Server Port" to something like 41194 to see if the default VPN port is indeed blocked by your isp. You could also try TCP rather than UDP.

 

[Sabbath81]

Would make sense to change the "Server Port" to something like 41194 to see if the default VPN port is indeed blocked by your isp.

tried that and the result is the same - cannot connect.

 

[Ripshod]

Then I think this is down to the fact that your router is getting a private IP from your ISP as @ColinTaylor mentioned earlier - possibly CG-NAT(?).
Is it possible to get a static IP from your ISP?

 

[Sabbath81]

Then I think this is down to the fact that your router is getting a private IP from your ISP as @ColinTaylor mentioned earlier - possibly CG-NAT(?).
Is it possible to get a static IP from your ISP?

yes, it is possible. But still - doesnt DDNS resolve exactly this issue?

 

[Ripshod]

Great question. The way I understand it CG-NAT is a method of sharing a single IP amongst many customers. This is fine for browsing, gaming etc, but should you want to contact your network externally there's no way to know exactly where to route the traffic, so it never gets past the ISPs servers. A static IP should resolve that as the IP will be exclusive to you.

 

[GSpock]

yes, it is possible. But still - doesnt DDNS resolve exactly this issue?

In order for your DDNS to work correctly, it must be assigned the correct public IP and that can only be done if your AX88U gets a public IP from your ISP or if the ISP modem/router does the necessary to match your domain name to this same public IP. Alternatively the static public IP will do the trick as mention by @Ripshod as long as it is matched to the correct domain name.

Can you provide an updated screen shot of your OpenVPN Server page ?

 

[ColinTaylor]

yes, it is possible. But still - doesnt DDNS resolve exactly this issue?

No. DDNS is just a DNS service. It doesn't do any more than that. I can see that DDNS is working from your first screenshot. I could resolve your DDNS name to a public IP address. The problem is that this public IP address is not the same address that your Asus router has.

C:\Users\Colin>nslookup azahariev81.asuscomm.com
Server:  RT-AX86U.home.lan
Address:  192.168.1.1

Non-authoritative answer:
Name:    azahariev81.asuscomm.com
Address:  93.155.148.10

 

[Sabbath81]

No. DDNS is just a DNS service. It doesn't do any more than that. I can see that DDNS is working from your first screenshot. I could resolve your DDNS name to a public IP address. The problem is that this public IP address is not the same address that your Asus router has.

the ISP told me in the morning that he has set it to static ... the problem persists

 

[ColinTaylor]

the ISP told me in the morning that he has set it to static ... the problem persists

Have you rebooted the router since then?

 

[Ripshod]

Changes like this can take a while. Often it's done overnight during network updates.
Presumably your WAN is set to automatic ip.

 

[Sabbath81]

OK finally the problem is resolved. Got new IP from the ISP, set as static, etc., so now everything works. COmpletely different addresses....