Catch 22 - Cannot connect to old version, which itself cannot be updated!

Hi all,

I have a Catch-22 situation with a mac mini (2013 model) that is running High Sierra (which is the last MacOS it supports).

Teamviewer 14 is running normally on it, however I cannot connect from my other PCs as I am getting a 'The remote TeamViewer is running an old version..." which it prompts me to update.

The problem is that I cannot update TeamViewer on that Mac, as the newest versions do not run on High Sierra. Therefore I am stuck -

I have tried downloading and installing older versions (down to 11) on my PC, but that still gives the same error!

This situation is ridiculous as the Mac is in a location I do not have easy access to - Can something be done remotely to at least be able to connect by using an older version on my PC?