Slowww Internet on Orbi RBR50 with 2 RBS50

I'd suggest resetting all the units to factory defaults and then reconfiguring from the ground up via the regular Orbi configuration process. If you haven't done that in a while, there's a good chance that bringing the configuration of the wireless system back to your desired settings from the defaults may well get your system back to working well. At least you'll be closer to a reference state, and the results of doing this will tell you something, too.