Recently I found frequently buffering when I watch youtube vids.
after do speedtest-cli in my OSMC, it bring me following:
Ping: 9.032 ms
Download: 1.60 Mbit/s
Upload: 18.89 Mbit/s
I tested many times, they all give me similar result, which is very odd:
the download speed extremely slow (only 1Mbit/s to 1.5Mbit/s) beside that, the upload speed without any problem.
When I do speedtest on my mobile phone in the same position of the OSMC Pi, it give me 70Mbit/s download and 16+Mbit/s upload, I think that should what the Pi got.
My Pi 3 B+ is about 4 meter distance away from the router, no wall or similar in middle to block.
Any possible adjustment to fix this low download speed issue? I am quite confused.
Hello,
Is it possible for you to make same tests with ethernet cable link ?
(to check if this is coming from wifi part or from network part)
Cheers
WiFi is always limited by the slowest device using the same AP on the same frequency.
Download on your android mobile phone a wifi analyzer software, and check how many other AP’s are broadcasting on the same channel as your AP. And do the test from the point of view of the AP.
When I was still using WiFi, I moved my AP to a channel that was not used by my neighbors 
wow!
thanks for your advice! very straightforward, very hit the point and informative!
I downloaded wifi analyzer in playstore, found my wifi are in very crowd channel, there are about 8 AP there.
I change my wifi router channel to another channel, instantly, my OSMC have speed:
Ping: 10.258 ms
Download: 35.86 Mbit/s
Upload: 18.08 Mbit/s
Even that’s not catch up the speed on my mobile, but that’s really OK for me to watch videos on youtube without frequently buffering.
Thanks @Smurphy, solution marked for your answer!
Is your phone using 5GHz?