UltraVNC not connecting

[Gordon1M]

Prior to acquiring my RT-N66U router, I successfully used UltraVNC on PCs within my LAN. Note that all of the related machines are in one sub-net and I am not trying to use UltraVNC from the WAN side. The RT-N66U is a replacement for a Linksys WRT54GL, which was running DD-WRT. I am running the latest version of AsusWRTMerlin and I didn't try UltraVNC with the stock AsusWRT firmware.

I have searched for solutions but most of the discussion is related to using UltraVNC from the WAN side. I don't believe that this can be a firewall issue, as I am just trying to use UltraVNC within the LAN. I did, in fact, turn off the firewall, but that didn't help.

Any help would be appreciated.

Gordon

 

[RMerlin]

Lan traffic is simply switched, so the router has no impact on LAN side clients such as UltraVNC. I would double check your IPs, since the new router might be using a different subnet, or you might be missing DHCP reservations.

 

[Gordon1M]

Thank you for the rapid reply.

What you are saying is what I would have expected.

The router and all of the PCs I am trying to connect to are all in the same sub-net.

I have checked that the uVNC server is running by telnetting to port 5900 on the same server machine. The service responds. When I, similarly, telnet to another machine with a uVNC server runnning, there is no respoinse. I have telnetted to port 25 on this same other machine, where I have a SMTP server running, and the SMTP service responds as expect, so telnetting in general between different machines doesn't seem to be a problem.

I have eight machines running on the subnet in question; two XP, two Win7, one Win8, one Linux, one iPad and one Android tablet. One XP machine and two Win7 machines are runniing uVNC servers. I can't connect uVNC between any of these machines.

Given the evidence, I would suspect that there might be an issue with the Windows firewalls, but I have turned these off and still no uVNC connection. However, I will try this again, just in case.

I suppose that there is no filtering that can take place within the switch function of the RT-n66u? Some of my machines are connected by WiFi and I am using MAC filtering for these, but I have not used these machines for uVNC testing. All of the machines involved are connected by Ethernet.

I have just thought of something. With all of these machines involved, I am using a couple of other routers (WRT5GLs running DD-WRT) connected LAN-LAN, so that there is still just one subnet. However, maybe I should re-check for uVNC connectivity between the two machines that are directly connected to the Asus router. That would eliminate these other routers from the issue.

Gordon

 

[RMerlin]

If some of them are connected over Wifi, make sure that you didn't enable AP Isolation on the router. A ping test should be able to confirm that they are truly on the same subnet, and not isolated from one another.

 

[Gordon1M]

After further testing, it appears that this is a Windows 7 issue with server machines and not to do with the Asus router. It may be a coincidence that I noticed the problem after installing the new router, given that I don't use uVNC very often.

I have found that I can connect to XP machines, which are running uVNC servers from XP, Win7, and Android clients but nothing will connect to the two Win7 machines that are running uVNC servers.

So, it seems that I need to investigate the Win7 machines.

Thank you for the suggestions.

Gordon

 

[RMerlin]

After further testing, it appears that this is a Windows 7 issue with server machines and not to do with the Asus router. It may be a coincidence that I noticed the problem after installing the new router, given that I don't use uVNC very often.

I have found that I can connect to XP machines, which are running uVNC servers from XP, Win7, and Android clients but nothing will connect to the two Win7 machines that are running uVNC servers.

So, it seems that I need to investigate the Win7 machines.

Thank you for the suggestions.

Gordon

Make sure the network profiles of the Win7 machines are set to Private and not Public. I've seem numerous cases where after a change of router, Windows would suddenly think it's connected to a public network (like a public hotspot), and would switch the network profile to Public, blocking all inbound connections by default. This can be checked in the Networking Center.

 

[Gordon1M]

That was it!

I didn't know that a router change would cause that. One Win7 machine's network profile had been changed to Public and the other to Work. I changed them both to Home and the server on the machine that had been changed to Public then responded to uVNC requests. The one that had been Work still wouldn't respond but then I found that there was no rule in the Windows firewall to allow this. Adding the rule solved the problem. I don't know what happened to the firewall.

Anyway, this is great and all is working now!

Thank you once more.

Gordon