So, I haven't installed its driver (not sure if this affects it). This is the USB adapter: https://www.tendacn.com/us/product/U6.html
I've tried putting it in another USB port, still the same it randomly drops. Sometimes it takes longer, sometimes it just immediately drops after I plug it in back. If I missed a valuable information, please just ask.
Btw, I use Ubuntu MATE 18.04.2 LTS (Bionic).