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Hardware Version :

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ISP :

My desktop pc, running win10, is connected to the LAN1 port of the D5 and i can access to D5 management page flawlessly
ISP cable is plugged to WAN port of the D5
Synology NAS ethernet cable is plugged to LAN2 port of the D5
The problem is that i cannot access to my synology nas page (192.168.0.8:5000) from my desktop pc. Connection to NAS through WIFI from any other device in the LAN (tablet, smarthphone, laptop) works flawlessly. Any other device ( with different OS) connected wired to the D5 has the same problem accessing NAS.
The problem go away when the internet is down or if i physically disconnect ISP cable from WAN port. It seems like that D5 is unable to manage traffic data on WAN port and NAS LAN port simultaneously.
Any help?
Thank you
G.