PrusaLink connection error  

PrusaLink connection error

Hi Guys,

Anyone have any ideas on this, 'cos at the sec I'm a bit stumped.

I was using PrusaSlicer 2.7.4, all has been working fine, no known changes that I am aware of - setup is as follows

Mac OS
Mini - reachable via PrusaLink directly, or via a Raspberry Pi running Repeater Server or Prusa Connect
Mk3S - Reachable via Repetier Server (effectivly using Prusa Link)
Mk4 - reachable via PrusaLink directly, or Prusa Connect

I tried sending a file to the Mk4 today from PrusaSlicer via PrusaLink - I get 

Error uploading to print host 
Couldn't connect to server 
[Error 7]

Same issue if I try and send to Repeater Server.
Same issue if I try to send to the Mini via PrusaLink

No API keys have been changed, and having just checked to be sure, the API keys are correct.

No problem uploading via Prusa Connect and I can connect fine to Repetier Server from the MAC, and upload directly to the Repeater Server console, so connectivity is there.

Upgraded PrusaSlicer to 2.8.1 - same issue ...