LTE3301-PLUS : ridiculously slow upload ?

So. I tried a few things. Like I switched the antenna, and saw that sometimes, I got up to 20x the upload (2Mb/s). …And also saw a new thing : the antennas plug werent properly… like not screwed well ? And so the antennas were wobbly. With the tip of my finger I could turn a bit the screw, and make the whole thing "to stand firm" as you'd expect it to be.

Things going well ! Then, at my 3rd attempt, it stopped working altogether. No amount of dwindling did a thing. My guess is that the antennas plugs were very easy to break (because I feel like I WAS very careful. It's a 200$ gadget after all).

It literally took my 1h to enjoy a faulty 4G router, then lost 1h trying to fix it, and finish with no router at all. I feel so very sad and tired to be honest.