Have a customer running GMS 204.
Suddenly SyncML-phones cant sync.
On the phone they get"Session failed Invalid server response".

Changes recently:
Upgraded to SP4.
Changed IP on outside firewall.

No problems logging i on Web-interface from the outside.
GMS-server is in contact with GW-system. (calender-entry and so on is
visible in web-interface)

Phones with real client works fine.

Any ideas?