Strange behaviour with Ethernet cable runnng on usb3 adapter

hi there,

to make a long story short, my touchpad with the pointer goes bezerk when i have the usb3 hub connected and i plug the internet via an ethernet cable.

the mouse (external) works fine - everything works fine when it's on wireless though.

If i plug the cable to the usb3 adapter BUT not into the router, the touchpad cursor is OK, just when you plug into the router and gets an actual connection, then it goes mad.

I cannot test with another router and Asus support suggested to try with a switch with i dont have, i tried with a usb3 hub - same thing happening - and i dont have any other usb to ethernet adapter to try.

This is odd and started to happen with this new connection we have which runs over the TV cable on coaxial.

The computer went into surgery few months ago for a battery change so might be related with that?

any ideas welcome - no biggie since wireless works very fast but still would like to use ethernet from time to time.

thanks,
Gabrio

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More context

in order to plug an ethernet i need to use an usb3 to ethernet gigabit adapter.



i
am experiencing errating behaviour with the mouse when i plug that
adapter, i did a bit of search and found someone with the same problem,
please see this article:



laptop - Why touchpad glitches when Ethernet cable is connected? - Super User



also,
could it be the power adapter of my router not grounded or something
like that? I am using ethernet via an internet connection with Ziggo
that comes off the TV cable.



when the Ethernet is
plugged, the laptops's touchpad starts glitching: can't move/press
buttons, cursor is oscillating even when I don't move finger. or if i
keep the finger on it will start moving oddly.



If i unplug the adaptor and stay on wifi then it's back to normal.

yeah i think i did try safe mode, same thing. but odd thing is that with another router in Germany, this didnt happen, touchpad cursor was fine. it's so random!