Hi @mjb,
Please check if there’s a firewall setting on your Panda Adaptative Defense 360º, then try to add spacedesk in the exception list.
The following are the spacedesk details you might need for manual setting:
service name: spacedeskService
file path: C:\Windows\system32\spacedeskService.exe
TCP/IP Port: 28252
UDP Port: 28252
Also please check if spacedeskService is allowed on your Windows Firewall settings.
Just open the Windows Settings -> Update & Security -> Windows Security -> Firewall & Network Protection -> Allow an app through firewall,
then check the list if “spacedeskService” is checked on both Private and Public.