weird happens

I had to change my wi-fi password after I found out someone was stealing my signal. This was no easy thing but I got it done. Since then my internet speed has dropped from around 590 mbs to around 95mbs (hard wired) My wifes computer is still running at approx 590mbs (hard wired also. I have reset my ethernet on my computer and also reset the router. I even changed ports on the router and the problem followed so by that, I can assume it is with my machine. I also tried the Winsock and Winsock2 merge mentioned in another thread a couple of times but no change. I can't figure out where to look next.
Running Windows 10 Pro and all of the computer info is in my profile. Or here: Computer type:
PC/Desktop
System Manufacturer/Model Number:
ASUS All series x64 based
OS:
Windows 10 Pro
CPU:
G3420 @ 3.20GHz 3200 Mhz 2 core
Motherboard:
ASUStek H81M-A
Memory:
16 GB
Graphics Card(s):
GeForce GT 440
Browser:
Brave
Antivirus:
AVG

spunk said:

Changing your WiFi password on your Router will not affect your Ethernet LAN internet connection.
Power Cycle your router (ie) Unplug the power, wait a few seconds and plug it back in. While waiting for the router to come back up, restart your computer.
Test your internet connection at Speedtest by Ookla - The Global Broadband Speed Test

Thanks for the reply Spunk. I tried this but no change. I had hopes but No Bueno.

I got rid of AVG but speed stayed the same.

- - - Updated - - -

Out of frustration, I decided to change my ethernet cable. It was bad and my internet speed is back to normal. (600Mbs)
Thanks for the replies from all. I appreciate the help to rule out all possibilities.