I got information from my UTM that a new firmware 9.601-5 was available. I installed it and after reboot I discover that all my NAT rules where not activated ! I had to go on each one and disable/enable them to get back the working setup :(
I did it with some of them and then reboot the UTM: again rules where not applied. Disable/enable them and evrything is OK.
For some rules I didn't apply the "automatic firewall rules" in GUI but had create myself the FW rules: those NAT rules where activated. But for NAT rules with forwarding ports to other physical hosts but *not the host himself and the VMs running on it where the UTM lies* doesn't matter which setup (manual or automatically), I have to activate "automatic FW rules" and disable/enable the rules to get them working.
No need to say that prior firmware versions didn't had this problem.
Does anyone face the same problem and confirm?