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RU Dedicated server inaccessible on network after router upgrade

Nijel Terry, User (Posts: 55)

Jul 17, 2018 1:19:05 pm EDT

Yesterday Spectrum had to come do some work on the cable connection and upgraded the cable modem to Wave 2 router. I forwarded port 5655 to my dedicated server as it was before but now when I am connected to the same network on the Viewer the clients all appear offline. If I connect my Viewer PC to my cellular hotspot network the clients on the dedicated server appear online and are connectable.

I don't know what is wrong. Can someone please help me figure this out?

Many thanks,
Nijel

Conrad, Support (Posts: 2926)

Jul 17, 2018 5:56:00 pm EDT

Hello Nijel,

Thank you for your message.

. I forwarded port 5655 to my dedicated server as it was before but now when I am connected to the same network on the Viewer the clients all appear offline.

This might mean that the Viewer PC cannot reach/communicate with your server PC. You should check if the DNS name of server can actually resolved on the Viewer side. Or, if you use an IP address, then there should be a direct route between Viewer and Server.

Nijel Terry, User (Posts: 55)

Jul 17, 2018 7:16:58 pm EDT

Support level: Pro

Hi Conrad,

Thanks for your response.

I am able to ping my server PC. It is using a dynamic DNS and I can ping that address on my Viewer PC and receive a response. They are both on the same network.

The only thing that changed from when it was working to now was the router controlling DHCP. I was careful to assign the new router the same IP range, the same static IP's I had before and the same port forwarding parameters.

Conrad, Support (Posts: 2926)

Jul 18, 2018 4:30:32 am EDT

Hello Nijel,

Thank you for the details. Unfortunately, it is hard to say why the server cannot be reached then since it looks like the problem is specific to the current network/router configuration than the program itself.

From you describe I can assume that you can access your server from the outside and cannot access it from inside the network. So this might have something to do with the resolution of your server's DNS name inside the same network where the server is. This brings us to the "loopback" problem when a service tries to resolve an external IP address from the inside.

Nijel Terry, User (Posts: 55)

Jul 18, 2018 5:21:43 pm EDT

Support level: Pro

Conrad wrote:

So this might have something to do with the resolution of your server's DNS name inside the same network where the server is. This brings us to the "loopback" problem when a service tries to resolve an external IP address from the inside.

I think you nailed it. I, as a test, went into my Viewer and renamed the server DNS address with the local IP of the server and my contact immediately appeared online. I can ping my server DNS name from the command prompt from within the network and get a response. It responds with my public IP address.

I just tried ipconfig /flushdns on Viewer and Server, nothing changed.

I'm really perplexed by this issue. It used to work fine on the old modem in network and out of network. I'm using noip.com for dynamic DNS and the app is running on the server keeping the IP address updated with the domain name.

Conrad, Support (Posts: 2926)

Jul 19, 2018 3:06:05 am EDT

Hi Nijel,

I think this is not about the end points, it's about the router. You might want to check with your ISP if your new router supports NAT loopback, or just generally describe the problem to them. They should be able to help because they know their known infrastructure better.

Hope that helps.

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