Hi @juratykokot,
Are both primary and secondary machine connected on the same local area network?
Do you maybe have VPN (Virtual Private Network) enabled?
Do you have third party firewall software on your primary machine?
For assistance, please also check troubleshooting – Network Connection chapter in the user manual https://forum.spacedesk.netuser-manual/.
For further analysis, could you please send us the following info:
Primary Machine
– operating system (Windows 8.1/10)?
– graphics adapter (AMD/Intel/Nvidia)
– network connection type (wired/wireless/USB tethering/WiFi Direct)
Secondary Machine
– Viewer type (Android/iOS/Windows/HTML5)
– network connection type (wired/wireless/USB tethering/WiFi Direct)