Can not connect to UNV Server 1.3.1

[Brian]

At my work site, i have installed UltraVNC server on one my computer to connect it remotely. I installed latest RC version 1.3.1. But when I try to connect from VNCviewer it says "Connecting" and I get to "Failed to connect to server". I have tried following things:
1. I can make loopback connection from that PC.
2. Added my PC's ip address 196.168.0.10 to Modem/Routers is PortForwarding with ports 5900 and 5901. I am using centurylink cT1000 modem. I have also made sure that vnc 5800, 5900, 5901 ports are allowed in IPv4 Firewall.
3. I connect using Routers IP address 187.x.x.x from viewer. I also tried using DynDNS address. nothing works.
3. I made sure that UVNC Server has auto ports -5900. and netstat -a -n shows that something is listening to port 5900. I tried chaning port manually to 5901 and netstat changes to 5901. Also tried connecting to this port remotely doesnot work.
4. I went to Security and MAintenance settings of Windows Firewall, disabled it even then I am not able to connect.
5. I checked app allow list for windows firewall settings and see winvnc.exe has Public and Private profile in allowed list.
6. I also tried to connect from this network from different PC. it does not work.
I couldnt figure out what is missing.
Can anyone help me this?
thanks
Brian

[Brian]

any pointer guys?

[Rudi De Vos]

1. I can make loopback connection from that PC.
First step ok
Do you have another pc on the the same 196.168.0.x network, just to be sure it works without port forwarding.
If this works, firwall rules are ok


Port forwarding that' harder to test.

You can use telnet to test connectivity via a cmd
telnet serv_ip 5900
If you are able to connect you should get
RFB 003.008
as answer
If you jhave another network service running on that PC you could try to forward that port and connect to that service ( ftp/telnet) just to check if the forwarding is ok.

You can install tcpviewer
https://docs.microsoft.com/en-us/sysint ... ds/tcpview
and verify if any data on the forwarded ports is entering the system