Second router or modem at same address

We are renting a house and sharing WiFi with our landlord who lives in the guesthouse. It's close to the main house, 100 feet , maybe. The router and modem is in the guest house. But there's minimal WiFi connection in the main house. There is a bamboo fence between her space and ours. If we go in the backyard speeds are 80mbps but once we go inside to the one or two rooms with WiFi connection the speed is about 30-50mbps.

Is there a way to either get a second internet account for the main house, maybe at a discounted rate? Or add another modem/router in the main house? we haven't tried putting her modem and router in the main house, I'm assuming then the guest house would lack in connection though. I've looked into the google nest but am hesitant since they are pricey and I'm not sure they would work

any help would be appreciated!