Thanks for the feedback.
Are you using the updated spacedesk Android Viewer app from Google Playstore?
Latest version is v0.9.84.
What is the current Quality/Performance settings (e.g. Encoding color depth/Rendering color depth) of viewer app?
Are you connecting over the wifi network (that goes through the router)? Is your network stable/reliable?
Can you please try to enabled the auto-connect option in the viewer app settings and check if it will help?