Cannot start sandbox server if I have Counter-Strike 1.6 running in background connected to a server

[khanghugo123]

Self-explanatory

I usually have CS1.6 running in the background. I cannot start a "Hero Sandbox" if I have CS1.6 running in the background connected to a server.

The disconnect message is "Disconnected from Server" with "Unable to establish a connection with the gameserver". This happens for both legacy and hl25 CS1.6

 

[khanghugo123]

This happens on Linux if that is relevant