I can confirm this behavior too. Signal loss when switching towers on my way to and from work. That started with late July builds, I skipped some. Not HW related (I have 3 Note4) and not network related, stock works just fine as does 0630.
So it's a couple of months later and I could not stand the signal loss and lack of re-connect of my
N910T (T-Mobile) anymore.
Ripee obviously has retired and the best working version he left is the one from Nov/07/2021.
There is no activity around the N910T (either working very well or given up for good?) and I was on the edge of tossing mine in the drawer.
But then I came across a discussion about modems and that there is an updated version -2020-
referenced somewhere by TMO.
https://www.t-mobile.com/support/de...note-4/software-updates-samsung-galaxy-note-4.
I unpacked both of the 910 and 915 firmware and found that only the modem.bin included in 915
has a date of 09/03/2020.
I thought to just flash the 915 modem.bin on top of my current installation but could not get
Odin to do that. Not modem.bin nor modem.tar (converted with WinZip/WinRar/7-Zip).
Tried that with most available versions of Odin.
I ended up flashing the entire 915 firmware from the Odin CP slot hoping it would just transfer the modem as someone suggested in this forum. What really happened was Odin finished the install successfully but my device would not start beyond the TMO start page.
Now I restored my latest Nandroid backup (with TWRP) and MODEM de-selected in the list on top of the 915 firmware. And I'm a happy camper. The signal strength is better than ever, I have reception in former dead zones and no signal loss on my daily drive.
I cannot say if the new (915) modem is responsible for the improvement (the files inside the bin are no different from 910) or if a new flash corrected something in Ripee's Nov/07/2021 LOS18.1.
But at least I'm confident to lift some of you who still hang on to N910T out of depression.
If you know how to flash the modem only -onto an existing installation- please don't hold back.
I want to run this thing for another year or two.