Hi I am hoping someone can assist.

I have an SXT router which I have my 02 sim card in
this in turn is connected to a mikrotik router in my house.

I am finding that it is quite erratic in that I am regularly disconnected
but then re connect again. When I am connected I get decent enough speed
etc.

I have NAT ticked on the SXT but not on the router would this be correct?
Or should it be ticked on the mikrotik router instead? or does it really matter?

Thanks for your time.

The fact that you sometimes get good speed, means your NAT setup is correct. otherwise it would not work at all.

I would personally use the SXT as a router and the other MT as WiFi access point but that's just me. It's just a personal thing and also I'd likely to power up the SXT from ether 5 of the indoor Mikrotik router . But yes, it does not really matter, based on information you give, where the NAT is.

I'd check signal level on the SXT, when you are disconnected / slow and compare it with that of when your speed is good.
also note which cell you are connected to, see if you are actually connected to a different cell for any reason.
also test with a phone when SXt is disconnected or slow, see if the phone can do any better.

further more, do speed test by directly connect a laptop to the SXT, so you know the problem is this part, not the other router.

check all interfaces on both SXT and the other MT, see if there is any TX/RX errors on the interface, which would indicate physical problem with wired connection between devices.

Thank you I will try that

I believe the 2nd MT is set as an access point (Home AP Dual)

will look into the other things.

Thanks.