If your tills come up with a message Hotel Server Offline when attempting to post items to the room in Caterbook, you will need to contact your EPOS provider to resolve this.
Caterbook and ICR Touch use a shared folder on the windows network to exchange Room and Transaction data between them.
The "Server offline" message simply means that the EPOS terminal is unable to access that shared folder. This can sometimes happen following a windows update, when new security software is installed, or when a member of staff changes the password on the machine with the shared folder.
The EPOS machine/s would need to be updated with the new access details for that folder and this is not something Caterbook are able to assist with.