Why does Mikrotik cut Wi-Fi speed when using lte modem?

Question

WiFi

Greetings! I assembled the Mikrotik RB951ui-2hnd system + Megafon Modem M150. I reflashed the modem to hlink firmware, the lte interface went up in mikrotik, I set everything up as expected, as a result, we have a speed of 30-40 Mbps on the wire, and a speed of 2-7 Mbps on wi-fi. I read somewhere that there is a problem with the power supply, that usb and wi-fi are powered on the same line, I decided to make an experiment, left the modem plugged into the Mikrotik, plugged the wired provider into ether1, measured the speed via wi-fi - 30-40 Mbps ... so the problem is not food, I thought.
I tried the modem with the official megaphone firmware, the ppp-out1 interface rose - the speed became 20Mbps on the wire, wi-fi 2-4 Mbps.
I usually use Mikrotik Hex Poe + Megafon M150, connect 3-4 Mikrotik RB951Ui to CAPsMAN for large country houses, no problems were observed over wi-fi 20-25 Mbps. And now it was required to assemble a compact system for a small office. And here is the ambush.
What could be the problem?

Answer 1

Greetings! I assembled the Mikrotik RB951ui-2hnd system + Megaphone Modem M150. I reflashed the modem to hlink firmware, the lte interface went up in mikrotik, I set everything up as expected, as a result, we have a speed of 30-40 Mbps on the wire, and a speed of 2-7 Mbps on wi-fi.

Download
https://mikrotik.com/download/btest.exe
and take wifi measurements to mikrotik.
The modem can be completely removed during this test.
Also show the wifi settings.