Connecting to ClientService of "Dennis" failed - CONNECT error during filelist construction

I have 5 clients running windows 8.1 pro in my domain network

the clients backup to a share on the network

for the last week they have been failing instantly when i run a full file backup or an incremental file backup

Connecting to ClientService of “Dennis” failed - CONNECT error during filelist construction

i have made sure clients are running on machine and they say they are connected to the server

This error occurs, if the server cannot connect to TCP port 35623 of the clients. Maybe the firewall config changed? See http://www.urbackup.org/administration_manual.html#x1-720009.3 for the used ports.

thanks for the advice, i have firewall disabled all together, which should allow any connection

i rebooted the server and still get the same error

anything else that could cause it ?

Did you disable the client or server firewall?

Both are disabled

Do you have a solution for the issue?