Wired is good.
SABnzbd can never get a higher speed than
http://www.speedtest.net/ reports. And please do note speedtest reports in bits per seconds, whereas SABnzbd reports in Bytes per seconde. Divide the speedtest score by 10 to get the Byte-speed.
Your ISP is Telfort, so my guess it that you have DSL (and not Fiber). Correct? With DSL your speed is not guaranteed. The good news is that Telfort is quite honest about the speed you can get based on your postcode: if you fill out your postcode + housenumber on
https://internetshop.telfort.nl/flow/bestellen, Telfort will tell the speed directly in the line under your postcode, for example "Maximaal haalbare snelheid op je adres: 30 Mb/s"
If speedtest reports a much lower speed than
https://internetshop.telfort.nl/flow/bestellen, contact Telfort about your speed problem. They can check the DSL line and your modem.
You wrote
Normaly i downloaded with a speed of 1.2mb/s but now its at 650kb/s.
Is that really a small "b", thus bits, or did you mean MB/s and kB/s (as reported by SAB), so bytes?
HTH