I want to use my 10G sfp+ as primary WAN on my RT-BE88U. But for my provider I have to setup IPTV. However, when I enter a value there, a message appears that this is only possible via the primary WAN. I think I could adjust this when I used my RT-AX89X as main router. Is this a bug in the ASUS firmware? Can I use this if I use the Merlin firmware?