LHGG LTE6 cell lock

Hey all,

I have installed my new lhgg lte6 - when i’m on a good cell i get a bit of internet, but after a while the modem decides to use cells which can’t provide… Tried cell lock and it just kills the modem, it just does nothing.
updated all my firmwares but still rubbish.
overall underwhelmed by my experience so far

Further to my setup, I’ve since tried 2 different carrier SIM cards which both offer cell locking and band locking as expected.
The one which wouldn’t work was a Three SIM, it just wouldn’t play ball - do different carriers program their SIM cards in different ways??
I’m currently using EE at 20km hitting 15-25 Mbps dl and 20-40 Mbps ul
Is the LHGG the antenna with highest gain?