By reset he means to do the factory reset, which puts the roku back to defaults, removing all changes made over it's life. Is that what you did?
Odd that it would be your new router. It is set to hand out IP automatically by default (as per user guide), and you say it does so for laptops. Are they connecting wifi or ethernet cable? I see in your user guide that the ethernet ports can be disabled, is why I'm asking.
If you haven't done the complete reset, do that before trying anything else.
"I might be moving to Montana soon..."