If the modem was really detected, go to IP-> DHCLIENT and add lte1 device, so that it would obtain an IP from the provider and also make it sure that the APN profile match with what your ISP expect
Stop that ! DHCP Client is used for USB devices who use a Ethernet emulation, like when your android phone use “Hotspot USB” or Huawei E3372 works in Hi.Link mode.
Normal lte modules inserted into m.2 or miniPCIexpress slot not use dhcp client !.
Default configuration at RouterOS should detect lte1 interface.
To connect to ISP you should use a proper APN, check that.
Use Quick Set like example: http://forum.mikrotik.com/t/lhg-lte-kit/142863/1
This should and provide PIN for SIM and APN of course.
This should in 95% give you internet even at connected devices.
Some ISP in USA can create problems but in EU this is all you need to start use device.
Three sim - I understand that is a name of your ISP/MNO
But i wanted to test an ee sim also before I decide which one to use permanently however when I test an EE Sim it does not work.
It does not show an internet IP address which I think might be the problem,
EE sim - it’s your next ISP/MNO then use his proper APN to receive internet.