Port sharing no longer works ?

Dear All

I used to have 10 different instances configured on the server with port sharing, there was a mixture of 2009/2015 and 2016 NST servers. Most of the time 3 or 4 NST servers were running in parallel with no problems.

I have recently added 2017 instance, removed 2015 NST and upgraded all 2016 instances to CU12-GB version and from that point onward I cannot get port sharing working.

All the services are configured to depend on Net.Tcp.Port.Sharing service. The AD account which is used as a service account for all NST services has been added to <allowAccounts> in C:\Windows\Microsoft.NET\Framework64\v4.0.30319\SMSvcHost.exe.config file.

It used to work fine but now is not.

I have installed 2017 and at this point everything seemed to be still working, I've had 2 NST one 2016 and one 2017 NSTs working fine for a short period of time.

It looks like installing CU12-GB broke the thing. I have installed CU12 by uninstalling previous version and installed CU12 from using setup, rather than overwriting existing binaries in Service folder.

Does anyone experiences anything similar?

Regards,
Slawek