Thanks in advance to anyone who can please help with this question.

I'm unsure how to position and wire in the eero 6+ system. There are a series of cat 6 network cables from each room of a house going into our garage and the fibre modem and an 8 port switch need to stay in the garage because the fibre connection and all the cat 6 cabling from the rooms go into the garage. From reading some threads, our installation plan was to disable the router and wifi functions on the hub supplied by our internet supplier. 

Originally the plan was to plug the cabling in as,

fibre modem with router and wifi functions turned off -> eero6+ no. 1 as main gateway router -> 8 port unmanaged switch -> eero 6+ no. 2 and no. 3. (there are also 3 TVs being hard wired into the switch)

The problem is now the location of the eero6+ would also have to be in the garage and the signal is terrible in that location because of thick concrete walls. I would like to place the first eero6+ no. 1 as main gateway in my living room and I think I have to run a loop of Cat 6 cable from the fibre modem in garage -> living room eero6+ as main gateway router -> back to garage with 8 port switch -> eero 6+ no. 2 and no. 3 in separate bedrooms.

Is there a way I can avoid this? If I leave the router function turned on from the internet supplier, can I go fibre modem with router function left on and WiFi off -> 8 port unmanaged switch -> plug each eero 6+ no. 1, no. 2 and no. 3 into the switch together with the 3 TVs? Is this possible and would that impact performance? Does this mean all 3 eero 6+ will be acting as access points? I read the first eero 6+ should be installed between the modem and the switch and will then handle the routing functions, is that right?