I was having similar problems with Intel AC-7265 installed in my HP Spectre x360. Slow speed and random disconnects, especially after Win 10 updates. I tried a lot of recommended remedies (use an older MSFT driver version, prefer 2.4 G band, limit channel to 20 mHz, etc.) and they partially worked.
The radical solution was to REPLACE the AC-7265 adapter with a more recent version, AC-8265 ($25 on Amazon) which is Win 10 certified. No parameter tuning was required, so far so good pulling full 60 to 70 mpbs that my cable account allows. My "recycled" AC-7265 adapter was later installed in another notebook and worked fine. So, give this surgical solution a try.