PBSXTR / R11e-LTE - LTE interface appearing & disappearing

Hi all,
I got a second hand R113-LTE router recently, plugged a SIM into slot “a” and it gave me internet connectivity asap without issue.

Yesterday I started playing with the bands on the LTE interface via winbox and all of a sudden the LTE interface disappeared.

Since then under interfaces the LTE appears for about 3 seconds and disappears for approx. 30 seconds repeatedly.

I’ve power cycled the device multiple times and even upgraded to routerOS 7.11

Has anyone seen this or can anyone offer a resolution?

Many thanks,

Josey

Update:
So I left the unit powered off over night.

Powered it up with sim in slot b, nothing happened.

Moved sim back to slot a and suddenly it’s working again.

I’ve managed also to update the modem firmware.

Everything now is working perfectly.

Very strange.

Resolved.

Even though SXT, there was some bug in the slot stuff in LtAP… maybe related:

*) lte - fixed LtAP mini default SIM slot "down" changeover to "up" after an upgrade (introduced in v7.10beta1);

But aligning the RouterOS to stable, the upgrading LTE and RouterBoard firmware versions too almost always the right first step…