Have you run Speed test tvOS app on all three checking the ping/jitter and making sure your connecting to a close server cross checking your router dns? If so, I’d wipe and restore one of them immediately. Set up as new, then turn on the setting to save your settings to iCloud, then wipe and restore the other 2 and restore them with the newly setup iCloud prefs: that way you don’t have to manually set up the other two.Update: Seems that updating my access points did help. One is still running slower speed tests than expected, but is usable.
Hope your work it out though 🎯