Skype and Wingate

[itgmorigia]

A win2kserver hosts a wingate server (last version at now). A win2kpro client with Wingate Client has skype (last version at now) installed. At starting the application works correctly but after sometime of inactivity (the user left the PC but leave the session open) the application do not communicate at all even if the green icon is displayed. Other internet skype users do not see the win2kpro user online. The only solution is to close and restart skype. The wingate gatekeeper shows the skype application and a TCP link to the skype server active but the skype application do not receive calls. Is this a wingate problem o a router (after wingate) problem?

[genie]

Do you see any firewall hits related to Skype service? We use skype quite a lot and it runs fine behind Wingate. What version of Wingate are you using?

[itgmorigia]

Do you see any firewall hits related to Skype service? We use skype quite a lot and it runs fine behind Wingate. What version of Wingate are you using?

Wingate version is 6.1.4, the firewall is disabled because the w2kserver has only one of the two nic enabled. Wingate is used for authentication and content filtering to WWW FTP and Socks services.
Content filtering is made by puresight.
Th firewall is on the hardware router after wingate and allow only 80, 25, 110 443,TCP out, 53 UDP out, GRE in/out, 1723 in/out. Is the firewall most restrictive for skype?
The skype application in wingate gatekeeper is always listed but after some time of inactivity it disappears from online.