4.11 swarm not working

yes, I posted exactly the same question with 4.10 and got it to work at least.
However, in 4.11, swarm refused to work and I have no clue what to do yet.

I copied C:\Program Files\Epic Games\4.11\Engine\Binaries\DotNET to every slave.

I edited the swarmagent CacheFolder, so it’s rooted correctly,

I edited AllowedRemoteAgentGroup to “Default”.

I edited AllowedRemoteAgentNames to “*”.

I edited the coordinatorRemotingHost to its IP adress.

I executed C:\Program Files\Epic Games\4.11\Engine\Extras\Redist\en-us\UE4PrereqSetup_x64 on all slaves.

I restarted all slaves. (10, btw)

I started the SwarmCoordinator on the Host (my local machine)

Every slave was identified corretly with the correct Swarmagent build. (1.7.2893.0)

I started the Light build in UE4. My local Swarmagent started calculating imediately.
4 of the 10 slaves popped up as well, but doing nothing.

Any Ideas?
thanks

Michael