>Sorry I didn't get back to your earlier. I have not tried disconnecting wifi because it is physically not easy (the router is in the corner with all kind of junk around it and the desk is in another room). But what I thought right now is I can disconnect the cable from the router and connect it to the cable modem.

It's been a while since working without router and I might misremember,
but I think you need a crosspatch if going directly to modem.

HTH

thomas