When you have VM router in modem mode you typically need a router in between your modem and the rest of your devices. Your router should provide LAN services regardless of the internet working or not. If you use VM router as a modem you should only expect one device to work with it.

Cheers
Tom.

Main: G61SL, 218, HD621, 2*7200SE, 7200HCSE, M6s, DSW, Apple TV 4K, NUC (Roon server)
Secondary: Wiim Pro, 3200, Audio Core 200
F80