Troubleshooting remote software support (click on this heading to expand/collapse)
Enabling Control-Alt-Delete services on remote PC's
Most common issues causing a connection to prematurely close:
Authentication failed - run the addsumremotesupport.exe as administrator
Multiple ShowMyPC sessions are running or are stranded in memory
Anti-virus software - temporarily disable
Another application may be currently using VNC (if so, end)
Windows firewall may be blocking port 443/others (see below)
Troubleshooting Windows firewall issues
List of what might be Windows may be listening to on a given port:
netstat -ano
The PID can be matched to the PID in Process of TaskManager
(click on View then Select columns to add PID if not there)
Other useful command line options:
netsh firewall show state
netsh firewall show config
Win 7/2008 Server:
netsh advfirewall firewall
Logging can also be enabled in the Windows Firewall, Advanced Settings
Pre Win 7:
netsh firewall add portopening TCP 80 “Open Port 80”
Win 7/2008 Server:
netsh advfirewall firewall add rule name=”Open Port 80” dir=in action=allow protocol=TCP localport=80
https://support.microsoft.com/kb/281336