I Encountered the same issue, allthough on a Windows machine and Android.
Spacedesk had been working great before.
Checked any Splashtop software: no,
Norton virus: OK, Spacedesk was allowed,
Rebooting software and machines didn’t work.
Network: OK, in same range IP.
But after removing the Spacedesk driver on my primary machine/PC (still used *WIN_10_64_v0967_BETA.msi), downloading the newest version (*v1013_BETA.msi) and (re)installing it, the issue was solved.
Kind regards from Trudy.