Hey there, @SamN.
Thanks for taking the time to reach out to the QuickBooks Community for support.
With this error message, I recommend consulting with your IT professional. This way, they can check all of your devices and troubleshoot the nonworking one. Your IT can run different tests and check all the connections on the nonfunctioning computer.
If you have any questions or concerns, please don't hesitate to let me know. I'm always here to lend a hand. Take care!