luman75 wrote:
All in all, I have a location very close to the BTS with visibility (300m in a straight line), so the gain of the antenna is probably not crucial for me. Apart from the antenna, is there any advantage of ZTE 830 over Mikrotik?
Then buy any mikrotik with a MiniPCIe port and a modem of any category. Even 18. Unfortunately, the price of such a modem kills, well above PLN 1000 for the modem itself

But 300m with visibility ideal. High modulation will go, it will go if it is (or will be) despite 4x4.
Do you have cable/fiber in your city?
Added after 3 [minutes]: luman75 wrote: I like Mikrotik because you can mount it directly outside and enter the building via ethenet.
For almost 2 years, some standard Huawei with the housing removed sits on the roof in an airtight can with short antenna cables and generally does not complain.