Hi,
Check whether Virtualizor service is running on slave server:
service virtualizor status
Also check if you are able to access the panel through below url from master using following command:
curl
https://SLAVE_IP:4085
Replace SLAVE_IP with IP of your server
Check ports 4081-4085 are not blocked on slave server.
If you still face the issue, create support ticket with Virtualizor to troubleshoot.