@Clive_A Unfortunately I also tried that way, it still doesn't work

@Clive_A Unfortunately I didn't solve the problem. I tried a lot of setting on the Windows pc I cannot access to, but I can't found enough on internet.

@Clive_A Thank you for your reply. Perhaps I didn't explain the issue clearly. My Windows PC on the main LAN (192.168.0.110) can access the Qnap NAS (192.168.20.137) through the file explorer,...

@Tedd404 After set mdns my windows pc (192.168.0.110) can access trough smb (windows file explorer) to my Qnap NAS (192.168.20.137) that's why I thought the prolbem was in the other two windows...

@Tedd404 Thank you for your reply. No, I'm not sure, I just saw smb in the Bonjour services and I thought it could work.

Hello and thank you in advance. I have created an mDNS rule to enable access from my main LAN (192.168.0.1/24) to my office VLAN (192.168.20.1/24) and obviously SMB is enabled in the Bonjour Service....