WS 2012R2 RDS Host Periodically Connection Issues

Hi all.

I have the next infrastracture:

1. DC on WS2008

2. New RDS Host on WS2012R2. Connection Broker and Licensing Server installed on same server. 

Sometimes (about every 10 days) connection issues occurs. Users try to login, pass authentication successfully, then they "freeze" when settings must apply. The same time logged users can work without any problem, after some time they get black screen, but server manager shows the sessions like active. I can connect via telnet to RDP-port, it looks like OK.

I solve the issue rebooting RDS Host till now. 

In event viewer I see that user group policy doesn't apply since the issue occurs. 

When we used WS2008 as Terminal Servers there was not the problem. 

Any ideas?