The VM Hub3, that you have, is rented. It’s a modem, router, network switch and WiFi Access Point. You can only have one per account and any bought externally will never work. The VM hub is a very basic device, underpowered and cheap to produce. VM will supply you with “pods” to extend the WiFi, but unless you are on the top plan they will cost £5 per month.
The VM hub can be put into what is called “modem” mode, it then just acts as a mode with all the other functions turned off. User can then buy their own networking equipment.
This could be:
1) An all purpose router, with network switch and Wireless access point.
2) A mesh system, but this would only provide 1 Ethernet connection, so if more are required a network switch is also needed.
3) Separate router, network switch and access point/s.
If you want full coverage of good WiFi, the best option for novice users is 1) but with an additional Ethernet wired Wireless Access Point upstairs.
I only have personal experience of business quality networking equipment so I cannot really advice on consumer products.
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