I need to take advantage of your expertise, if I may?
As the thread title states, we live in a high-rise flat so have concrete walls and are having a problem getting decent signal into the furthest bedroom. We are on the M600 tier and use a Super Hub 3 in router mode. We used the connect feature to detect dead spots and were offered free extenders. They worked well but always ran VERY hot and, recently, the main unit died in a blaze of smoke and bangs! Because of this, I'm not confident of simply getting a replacement as I'm worried about it being a fire hazard! As a temporary measure, I'm using an old Netgear EX2700 but this, obviously, doesn't support high speeds so my daughter is struggling to keep a Zoom conversation going while in Lockdown. Should I switch to modem mode and get a separate router or is there a fault with my Hub?
No you put the Hub into modem mode and connect the first Mesh unit to become the router (NB there is a set sequence for doing that - just ask if you get that far).
The first Mesh unit will have an extra ethernet port so you will need to ad an Unmanaged switch with GB ports to that and then connect your ethernet devices to that. These are around £15-30 depending on how many extra ports you want.