RBK23 or RBK50 for one story with yurt

My friend has a 2000 sq ft house and a yurt in the back yard.  Their current (Very old) wireless router has issues getting reliable 5GHZ signal to the far rooms (50 ft away through 4 walls).  They also want to have good signal in the yurt which is 30 ft from the router through the one outer house wall.  They have 120Mbps internet through their ISP.  The RBK50 seems overkill for their ISP speed.  They may or may not need the 2 satellites you get with the RBK23.  Pricing is about the same on both.   Any suggestions on which would be the better choice to get stable internet to all areas?  From a load perspective, they have around 10 connected devices and need to support 3 or 4 simultanous video calls or 2 video calls and netflix.

Thanks!