CheckPoint 5000 Dropping Skype for Business Conversations

[gjovanovski]

Hi,

We are having the following issue:

Skype for Business conversations are dropping when the partner is using the older Lync infrastructure. All of the Skype ports and applications are whitelisted by policy. Those same conversations work and do not drop when the employees are outside of the company network.

Only thing that is being blocked around the time that the Skype conversation drops is the 443 traffic to various Microsoft owned IP addresses with the info "TCP packet out of state, First packet isn't SYN".

Disabling "Drop out of state TCP packets" is out of the question.

Does anybody have a similar problem or a solution? I am here for more info.

Thanks.

[PhoneBoy]

That may be a red herring.
Is this a cluster and are there any failover happening around the same time?