Low upload despite 100k line in Streamlabs OBS?

I have the following problem:

I would like to stream Shadowlands via Twitch, which is unfortunately not possible at the moment, because my upload rate in Streamlabs OBS or OBS Studio is extremely low (sometimes fluctuates between under 1000 Kb / s to 2500 Kb / s) and that although my internet speed is at 100 Mb / s download and between 9-10 Mb / s upload. My PC components are not the best (DDR3), but in my opinion they should be sufficient for normal streaming (no still images, extremely pixelated).

CPU: I7-4790K @ 4.00 GHz

Graphics: Radeon RX 590 8GB

Mainboard: ASUS Z87-C

RAM: 16 GB

Power supply: 650W

If you still want to know something, please ask! I'm grateful for any help!

Your PC components almost certainly have nothing to do with your upload. Search the internet for speed measurements. They are separated for upload and download. Then you will know whether it is your line or not.

According to various speed tests, my down / upload, as already described above, is in the range of 100 mb / s download and 10mb / s upload.

I'm afraid then you can only call your provider once. Complain if it is under your contract (it is often the case) or ask about the test for an upgrade.

Tomorrow I go to my friend's place with my PC and then test if it's really because of my internet. If so, I will definitely call my provider.

As expected it went smoothly even though he only had a 50k line. Oh thank you for the tips.