I need to solve the wifi black hole downstairs. This seems decent for the price.
5 GHz: Up to 867 Mbps
2.4 GHz: Up to 300 Mbps
TP-Link AC1200 Dual-Band Wi-Fi Range Extender wirelessly connects to your Wi-Fi router, strengthening and expanding its signal into areas it can’t reach on its own. With speeds of up to 300 Mbps on 2.4 GHz and 867 Mbps on 5 GHz fast Wi-Fi in every room and say goodbye to dead zones.
Set up and manage your Wi-Fi through the TP-Link Tether app from your smartphone (Android, iOS)
If it's a range extender don't bother, you're better off investing in a cheap real mesh setup.
Range extenders "strengthen" your signal but cut your speeds down quite a lot when connected to that node.