While doing the Linksys RE7000 setup for the first time, if you are getting some errors, you might use the wrong details. Or you just skipped any point from the process? This happens when you are not aware of the setup procedure or fill in the details imperfectly. So, use these points that we are going to tell you and check them out to fix the setup errors. You might place the extender too far away from the existing router which you should locate near the router during the process. Or there can be some electrical things near the extender that are interrupting the signals. 

So, check that the location you choose must be free from metallic and electrical appliances. Also, it must not be closer to the thick concrete walls which can make the signal strength weak. Apart from that, there must be a strong enough connection between your extender, router, and device. Whether that is wirelessly or wired. Here keep in mind that you need to use the default login and other credentials as you are setting up the extender for the first time. Lastly, reset the extender if the errors still persist, and do the setup after turning it into the factory default state.