You see this is where I am going when I say we want the more "Commercial" offerings, with some of the Mikrotik's they can be powered with active PoE or passive PoE with 18-57V, all the cost and effort involved in getting 220V closer to have a shorter run of 12V when you can just push 48V with a simple ethernet cable and call it a day.This is the right way to do it. Get the LTE router as close as possible to the external antenna. There is also an issue with voltage drop with 12v power supplies over long distances so if possible you also need to get the 230v mains supply as close as possible to the router as well to minimise the length of the 12v cable.
Not to mention depending on your router you could then even power cycle your modem if you needed to if it's getting power from the router which could be handy.
Some other cool features on the SXT LTE that I quite like is that not only do you have PoE in you also have 1 PoE out on there, very handy if you have a small site that has say one IP camera at a gate.
On the SXT LTE you also have 2 simcard slots, so you could also theoretically have a failover sim which could be handy (I have not tested that before though)