@AnonymousRetard thanks for you reply,
I finally managed to complete my setup like this.
66bbb74c-86a6-4079-bf3b-17e90ede9090-image.png
To do this, you had to perform additional actions on the switch. I created 2 profiles.
1 - With the LAN in untag and the VLAN20 which is tagged
2 - With VLAN20 only
Then apply profile 1 on the port where the LAN arrives and apply profile 2 on the port where I want to connect the equipment (including my PC).