RBwAPR-2nD&R11e-LTE Antenna question

Hi,
I’ve a RBwAPR-2nD&R11e-LTE router. I seem to be on the edge of the LTE coverage map and connectivity is not the best, there are frequent disconnects. Interestingly the connectivity is much reliable on my phone (Samsung S10e).
I figured I could connect an external antenna to it improve the connection. Is it possible to connect an external antenna on this router?
I saw the mANT LTE 5o antenna being offered as an accessory so I’m guessing it is. If so are there any instructions available how to do it? I didn’t see an obvious way to take apart the plastic housing beside removing the cover which give me access to inserting the SIM card.

As for the mANT LTE 5o, are cables included? I think I would need 2x “pigtails” and two cables to connect the router and the antenna. I’m not sure about either the pigtails or the cable type. What exactly do I need?

The mANT LTE 5o is an omnidirectional antenna. Is that what I need or I should be getting a directional antenna to focus on just one tower? I used my phone to look for towers and there seems to be a few around so I’m not limited to just one.

Thanks for all the information.
regards,
bstoth