Remote Desktop/Telnet with Dial-up VPN not working

All remote users to my office (including myself) suddenly cannot connect to their PC’s or a RISC within my office.

I can log into my network and remote to the server but cannot remote desktop to my office PC from home or our RISC using either my software or just going to TELNET xxx.xxx.xxx.x of the RISC itself.

I do get an error saying “Connecting To xxx.xxx.xxx.x …Could not open connection to the host, on port 23: Connect failed

Thanks for help!

Jason