R8500 - Nighthawk X8 AC5300: No Internet with VLAN/IPTV enabled - Please Help!!

Hi, 

I have tried to get my Telenor (in Norway) fiber to work with my R8500 for both Internet and IPTV. Its like I can't have WAN and VLAN at the same time. The router immediately loses internet with VLAN/IPTV enabled. Internet by itself is no problem, but there is no Internet when VLAN/IPTV is enabled. My ISP (Telenor) can't help me because I don't use their Wi-Fi router. Can anyone share their experience? Do anyone have an idea of what I am doing wrong?

I have  followed exactly the instructions to enable VLAN/IPTV: 

- https://kb.netgear.com/25724/VLAN-tagging-setup-for-Nighthawk-router.

- https://kb.netgear.com/29911/Configuring-VLAN-IPTV-setup-on-your-Nighthawk-router 

I have reset the router to factory default and installed new firmware (V1.0.2.144), but the issue is not resolved. 

Thanks for any assistance!