Wireless Joint

I'm attempting to implement a remote network on an Island. I've acquired a Netgear LB1120 cellular modem as the cloud connectivity device. Due to relatively poor cell coverage I've also acquired and installed a WeBoost Cellular repeater. The local side uses a conventional ASUS router with a selection of PC's, dedicated hardware, and a Raspberry Pi. Among the issues encountered are:
1) The cellular network seems to disconnect the modem at random intervals and the modem does not recover the connection. This is not understood since the cellular repeater provides signal strength in excess of 4 bars.
2) The modem is stuck in 3G mode.
3) I can only initiate an inbound connection to the remote network by using a type of remote desktop software called 'Splashtop'. This works but is not entirely satisfactory due to the need to keep a Windows PC running at the remote site.
4) KASA smart home devices do seem to work correctly for inbound control when the cell modem link is up.

Questions:
Is there a way to have the LB1120 re-connect automatically after the link is dropped?
How/what can I do to get the modem to connect with LTE? My phone is able to through the repeater, why can't the modem?
DDNS does not seem to work for the inbound connections. Is there an explanation for this? What methods/configurations are being used by KASA and Splashtop to enable inbound links?

Thanks in advance for any insights.

Hello,
From my personal experience boosters have been awesome for getting cell phone service. Still use one today at the house for our cell phones.
When it comes to LTE modems haven't have much luck with them. It is like they are surging all the time and it will drop it. Had the exact same issue with a LB1120 with a WEboost cell booster.
What I found that I was better off getting the modem hooked up to mimo antenna set up with out the booster.
What I use today and seen others do on this site. Not only is the connection more stable but is faster as well.