Cannot find Sonos system on my Windows 10 PC, cannot add Sonos 1 to network

I've recently added three Linksys Velops to my network, they work fine with everything except Sonos. At the moment I have two issues:

• Cannot connect my PC Sonos controller, it cannot find Sonos system (PC connects via ethernet cable, no Wifi).
• Cannot connect my Sonos 1 speaker to the wifi system (which does show on my Sonos controller on my mobile). I can find the speaker on my mobile, but it fails to connect. I guess due to weak wifi, but I have plugged into ethernet connection as well.

I have the following:

• Virgin (Netgear) Super Hub 2 router to Virgin cable broadband.
• 3 x Linksys Velops.
• 1 x Sonos booster (downstairs)
• 2 x Sonos S5 (downstairs)
• 1 x Sonos One (upstairs)

My mobile Sonos controller shows 2 x S5, not the Sonos One.

On my PC I am trying to 'connect to an existing system)'.

Can I assume that Sonos Boost doesn't produce enough output to connect to Sonos One upstairs? If so, a bit pointless! How best to place it to supply signal to the three speakers? Is there app that shows signal strength in each room?

Do I have to add a new Sonos system to my PC?

Thanks in advance for any help.