@woozle Precisely correct and i did as you suggested, it really was as shrimple as that. Standalone app does show correct speeds +-. Thank you so much. Thread can be closed now.

@Tori9th

@Joseph-TP Router is modern enough, ASUS RT-AX55. Speed readings were fine when used before on z370 motherboard with integrated gigabit port. Cable also stayed the same and was not damaged in the...

@woozle Performed via speedtest on several different servers. Also attempted through similar service for the same result.

I have a very poor quality PC atm, it's an old iMedia s1300 from Packardbell with am3 processor and da061l-3d motherboard. Onboard nvidia lan can only run 10/100, so i decided to get an affordable...