Regarding Skype, the only way I managed it to work with Web Filter in Block All/Allow only specific IP address mode, was to put my IP address in "Skip transparent mode source hosts/nets" (when proxy in transparent mode) with Allow HTTP/s checked...
Immediatelly after that Application log showed real IP instead proxy IP, and the host was allowed access by rule #3 instead block by rule #4 (screenshot).
Regarding Skype, the only way I managed it to work with Web Filter in Block All/Allow only specific IP address mode, was to put my IP address in "Skip transparent mode source hosts/nets" (when proxy in transparent mode) with Allow HTTP/s checked...
Immediatelly after that Application log showed real IP instead proxy IP, and the host was allowed access by rule #3 instead block by rule #4 (screenshot).