Boosting Orange LTE Internet Speed: Tajfun DSM1800 Antenna for 1800MHz Band & Airbox LTE Modems

I warmly welcome!
I am asking you for help colleagues.
Well, I signed an Internet contract for a home in Orange. 150GB per month in the package, 00.00 - 8.00 download without reducing the package (Happy hours).
The problem is that in my room (where the Airbox LTE modem is to stand) there is poor LTE network coverage. The download speed is around 1.5 - 3 MB / s, which is very little. I did not get away from Disney so I do not believe in full speed cartoons etc., but I would love to improve the Internet parameters. So I came up with the idea of buying an LTE amplifier. Being familiar with this topic a bit, I read that I need to amplify a specific signal. Orange has an LTE 1800MHz band. Based on this information, I found the antenna that I would target first:
Tajfun DSM1800 (on the allegro for PLN 399) 19dBi gain, I can't provide the link, but I think you can easily find

I will add that the distance between my house and the transmitter is about 2km in a straight line (it is located in the same town, in the attachment there is a bts map with my location and the transmitter marked)
Probably someone of you will notice that I will give a modem (Airbox LTE) I don't have an external antenna.
Therefore, I would like to ask you to provide examples of models (with a sim card, of course) for modems that could meet my requirements and match the antenna above - if it is worth buying.
A lot of it, but better too much than on the reverse ROT
I am asking for a quick answer Thank you in advance and hear you soon

PS If I did something wrong (on the forum - place or topic or anything else) I am asking you to correct it or instruct how to do it) Thank you

If I were you, I would resign from the contract with Orange, with such crap. You chose the worst as you can, the Alcatel MiFi is not worth even 1 PLN. Another choice, i.e. some pseudo amplifier for PLN 400, is no longer a mistake but a grim joke. And to the set you show some illegible screen with a pseudo map from the salesman chlamam or new-electric. Such "companies" are bypassed wide. You also need to know that in this offer LTE Internet for home router only router with LTE-A for PLN 0. It is worth PLN 500-600. That's all you have to give on the free market, since you haven't subscribed, the alternative is B315 for PLN 300. You have coverage with the BTS LTE1800NetWorks in Donimierz or LTE800 with the BTS Orange in Pomieczyn Mały 29. You need to do tests on a phone with LTE with the Network Cell Info application outside and speed test. It will show BTS data and LTE signal parameters. The same tests for BTS in Donimierz and Pomieczyn. LTE800 range greater. Speeds depend on the BTS load. T-Mobile customers also use Donimierz LTE1800NetWorks.

By enclosing this information I did not want to somehow show great knowledge on this topic because all I read was only such basic information. Somehow, I never believed the BTS map, but it is one of the clearer maps that I found and used to better illustrate the situation and give as much information at the very beginning about where I live, how far away from transmitters etc. and not so that you could base just on the map I gave.
I know that this modem is what it is, unfortunately I saw it because of the fact that it doesn't have an external antenna, so it was too late. I also took part in the contract with PS4 Slim 1TB, and in the package with this equipment and this internet, in addition to A. LTE I had, I could choose Airbox Plus 2.0 which has the antenna input. However, I would like to exchange it on my own for some more powerful equipment, so I didn't care so much the more that I would like to improve my range anyway and I can do it only through a kind of amplifier.
That's why I asked the forum users for advice.
So please calmly say what should I do or what would you do in my situation?
I mean mainly the equipment you recommend that could improve it a bit (I now know that I made a mistake catching this internet but I will not do anything about it because the contract was signed in the salon) so I am looking for a lifebuoy in the form of equipment.
Despite everything, thank you for the comprehensive answer and I hope that with your advice I can do something about it.
greetings

The map is only http://beta.btsearch.pl/?dataSource=ukelocati...ds=lte&bands=?er=54.46278%2C18.203833&zoom=12, the one from a shanty trader is a misunderstanding. At present, you don't have LTE-A in Orange. There is no LTE800 and LTE2600 Orange on the BTS Network Donimierz, even there are no permits. In Pomieczyn only LTE800 works, it is not known if and when it launches LTE1800 because on LTE2600 rather not. For LTE 1800 or LTE800, all you need is a B315 router, cost 250-300 PLN (only not with T-mobile). A router with LTE-A or E5186 costs 450-500 PLN. Of course, no amplifier, only an external antenna for the selected band. But for this first mentioned tests, on LTE1800 dual LTE1800 MHz antenna, to LTE800 with BTS-a Pomieczyno 2x ATK-10 / 800-980 or ATK-20. On LTE1800 Networks T-mobile and Orange have 15MHz bands in MIMO and DL up to 112Mb / s, on LTE800 Orange has 10MHz in MIMO and DL up to 75Mb / s. You need to check which band has better speeds. The LTE800 network is new and good on unloaded BTSs, LTE1800NetWorks works differently. hence the need for testing.