qBittorrent official forums

So.. i have problem with qBittorent.
i want to get maximum possible speed but can't 
My speedtest:

What result i get with qBittorrent(default settings all)

How i can fix to get full download, upload speed?
I think problem is with disk cache.
qBittorent is on SDD
I save torrents on HDD.

As I've previously stated in my...
EXTREME Speed Tests of various BitTorrent Apps
https://qbforums.shiki.hu/index.php/topic,3956.0.html

...reaching 100 MB/sec using qBitTorrent is extremely hard even under perfect conditions.
I had to use a ramdrive capable of >1 GB/sec speeds to do the tests!
I used TCP instead of uTP -- since uTP seems to struggle to break 1 MB/sec when using 1 seed and 1 peer.

On top of all that, maybe the peers/seeds you're connecting to are slow?

In my case i want to get ~70-80 mb download and at least 20-40 mb upload.
if i up disk cache to 1048 mb i get 100-110 mb download, but after 1 min it's down to 3-5 mb.
How to fix this?
CPU: i7-8750H

Hopefully you're running qBitTorrent v4.1.5 and update when the next version comes out. qBT v3.3.16 was reasonably stable as well, but lacks a few features (like disk coalescing) that improve speeds.

In BitTorrent settings...
If you're only doing private torrents, you can disable DHT, PEX, and LPD...but PEX is good to leave enabled if you sometimes use public torrents.
DHT uses far more connections and is also useful on public torrents that have dead trackers.
Local Peer Discovery is unlikely to find peers/seeds on the same ip range subnet as you (as though they're on the same LAN as you)...and those it does find are probably available through tracker updates, DHT, and PEX anyway.

Torrent Queueing has a few bugs that probably makes it better to stay disabled.

In Connection settings...
Disable uTP on busy torrents, because TCP speeds are much more reliable and faster. (qBT/libtorrent's uTP handling is buggy.) On torrents with few peers/seeds, you'll need uTP.
Disable UPnP/NAT-PMP -- if you're using a VPN or proxy, those are harmful because they forward the wrong network interface. (No need/point in forwarding qBT's listening port on your router if using a VPN or router.)
If not using a VPN or proxy, a manual port forward on your router/gateway is more reliable anyway.

In Advanced settings...
Disable "Resolve peer host names" -- these are often garbage and even sometimes faked to look like something else. It requires making additional connections to do as well.
Disable "Resolve peer countries (GeoIP)" -- these are sometimes wrong and not terribly helpful if you want more speed. It requires making additional connections to do as well.
Disable "Download tracker's favicon" -- this puts additional load on every tracker, which is especially bad if you are adding 20+ trackers to every torrent.

CORRECTION, NOT NECESSARY -> No need to disable "Send upload piece suggestions"
(I retested "Send upload piece suggestions" with qBitTorrent v4.1.5 and didn't experience the slowdowns I did in the past.)

Do NOT set cache size larger than about 1100 MB for qBT 32bit version! It can cause an out-of-memory crash. (32bit apps cannot use more than 2 GB normally.)
Set "Disk cache expiry interval" to 600 seconds (max allowed) to prevent the cache needlessly throwing away data -- it may help more than making the cache size larger than 500 MB.

Make sure "Always announce to all tiers" is checked and remove dead/irrelevant trackers from public torrents. (An irrelevant tracker is one arbitrarily added that is extremely unlikely to find other peers/seeds.)
Disable "Always announce to all trackers in a tier" -- that can actually get you banned from trackers, because you'd otherwise be announcing on their HTTP, HTTPS, and udp trackers all at the same time.

with this settings upload is around 700 kb - 2 mb
how i can up upload speed?
Download speed stay around 50-70 mb and it's good for me.
But problem i have is with upload speed..

Maxing out upload speed is probably only possible if there's not a lot of other seeds uploading to the "hungry" peers.
When seeds outnumber peers, then you probably can't upload quickly to peers because everyone else is trying to as well!