I have a 3 storeyed home with basement. The coax cable is in basement. So is my dual Modem/router. I have concrete ceiling in each level. My package is 100 mbps

I was not getting wifi signal on top floor so I used following setup:

Modem/router in bridge mode (basement) > connected to gateway eero device with ethernet (basement)> netgear gigabit unmanaged switch> this device connected to another eero with ethernet (top floor)> another erro device in middle level connected through wifi

The speed test shows 98 mbps speed but when I am streaming video it keeps buffering. When guests come the speed suffers as well