Need more info so we may help you. Model and version number and what type of issue are you having?

If the default userid and password does not work, then the method is to reset the router to factory specs and re-enter all of your settings including a new userid and password.

A network hub will work if you have bandwidth or use a network switch. See https://eastmanreference.com/the-difference-between-an-ethernet-splitter-a-switch-and-a-hub for more info. If the room...

@Dietmar Have you tried a reset to factory? I know that is not fun as you need to re-enter all of the router settings but it may help you in this case.

If it were me, I would do the return.

I have held off on going to Catalina because of this and other apps that do not support 64-bit. I used the go64.app to see all the things that may not work. Things like Quicken, Beyond Compare, Word...