Veyon config on dual Win/Linux

[Marqui]

hello guys,
I am having trouble configuring Veyon on a set of 20 PCs all in the same room.

Previously, this heterogeneous set worked fine and I could monitor all the PCs (except some Raspberry). Since an update, nothing works anymore. I can no longer access the computers from the master PC. The workstations are located and present on the screen of the Veyon master but they are not connected (empty screen) and I can't act on them (except 2 PCs under Windows 10).

Description of the room :
All workstations belong to the workgroup "S 102".
All workstations belong to the internet network "S 102" (192.168.230.XX).

20 workstations:
13 PCs in dual boot MX Linux/windows 7 pro - Veyon 4.3.2
1 master PC under MX Linux - Veyon 4.5.2

2 workstations in Windows 10 pro - Veyon not yet installed
2 win 7 pro workstations - Veyon not yet installed
2 workstations in MX Linux - Veyon not yet installed

On all computers, I have created a "student" session and a "teacher" session. On the 13 workstations in dual boot, the Windows 7 session is very rarely used, they work 99% of the time under MX Linux.

On Veyon config :
I have entered the IP address of each configured workstation
I created 2 keys (1 public, 1 private) and I distributed the public key on the client workstations.
I installed veyon master and client on all the workstations on the "student" session.

On Veyon Master :
All the workstations in the room are marked on the screen, but the only workstations I can act on from the master workstation are those on which I have not installed Veyon (????): 2 workstations under win 10.

I must have made a mistake when I reconfigured the system. If someone could describe me his installation with pictures of his configuration, I think I could fix the problem.

Thanks in advance to those who will take the time to read me.

Happy Holidays!