Oh, you need a router only then!
In this case I would take a completely different approach and build a pfSense router based on Intel x86 (i5/i7) with 8/16GB RAM, 60/120GB SSD, PCIe Intel Gigabit NICs and use the existing Orbi APs. You can buy one from Netgate, but the price is very high. It requires a bit more technical knowledge and is not that user friendly to setup, but no consumer router can beat the performance. And you can actually enjoy your Gigabit Internet connection with no limitations, plus you can have great network control and monitoring tools. With 50+ devices, 4K streaming, probably NAS file sharing and Gigagit Internet connection I wouldn't recommend any consumer grade router.