Which 2012 r2 VDI / RDS Servers can I reboot without kicking my users?

This was the question at work. Can we reboot certain servers without really effecting currently connected users? There are two roles you can do this with:

RD Connection Broker & RD Licensing Server

If you reboot the RD Gateway/RD Web Access Server (which are on the same system in our lab setup) it will disconnect any active sessions on the VDI environment.