Fios provided router signal weirdness on 2.4G [ CR1000B ]

Hi,

Switched over Fios from Spectrum, getting solid connection through direct Ethernet to router, and good 5G / 6G speeds with Fios provided router [ CR1000B ] and a lined wired access point. Getting very bad speed, dropping as low as <1Mbit/sec on 2.4G channel. Prior to Fios, I was using an (first gen) Orbi mesh, and did not have any issues at all between (5G) / 2.4G. The Orbi mesh is REALLY old, and I had been wanting to update the router; and I thought the Fios router would be an upgrade in general. I isolated the issue to the 2.4G channel on [ CR1000B ]; disabled it, running the units on 5G/6G, confirmed all devices have good speed. I have confirmed, I don't have any devices that needs to be on 2.4G, so for now, running whole household (around 15 devices) on 5G/6G. Does anyone have any experience with the 2.4G issue on [ CR1000B ] (short of replacing the router, which I prefer not to ($$$), or turning off Fios wifi and reverting back to my first gen Orbi)? Thank you.