Reliability of Linksys ea6900 and ea6350

[Christos]

You can get a cheap Xiaomi Mi Router 4A (Gigabit Version) and install dd-wrt (search instructions on youtube).
Using hardware offloading, it can achieve gigabit internet speed and will get software updates for a longer time than many consumer routers.

 

[Tech9]

and will get software updates for a longer time

Probably not. Both DD-WRT and FreshTomato projects are on the way out. Old hardware, old kernels, old drivers. With NAT acceleration enabled, in case it works properly, the most interesting firmware features are lost. Everything new is closed source.