Firstly the Hub 3 is better than the Hub 4, well that was what an engineer told me, They have less complaints about them. Took one look at my Hub 4 and removed it.

For the last 30 years I have added additional Routers setup as WiFi access points, (this was suggested by a network geek at a company I worked at, the advantge being if you setup the WiFi different to the HUB, any Hub upgrade or exchange, you dont have to reset your WiFi network), connected by cat5e to the main VM supplied hub, nb this work in normal mode or Modem Mode you dont need to set as this, I never have.

You can get flat cat5 or 6 cable from Amazon which is easy to tuck under skirting boards, in upto 30 meter pre-made lengths. So you can then put a router in a centralised location or as far away as the cable allows. This is what I use for my CCTV cameras on 2.4 & the 5.0 for faster devices. 

For a MESH system you really need Tri-band, so they communicate on 6.0 GHz, leaving the 2.4 & 5.0 free for WiFi. 

You cannot replace the Hub3. You can buy your own router & put the hub in Modem Mode.

Hi ZZoom,

Thanks for posting and welcome to our community 😊

Sorry to hear you're getting some slow speeds, I've had a look at things from our side and found no issues. 

How're things since you posted on Monday? Can you confirm if you've reset the hub?

Alex_Rm