Extender seems to have stopped working

One of my motion sensors quit responding and in troubleshooting it I moved it closer to the base and it worked fine. I had another motion sensor and installed it with the same results. I did get a message that the extender had gone offline but came back online an hour later early this morning. It still showed up in my devices so I removed it and now trying to install it again it is stuck at "waiting to connect to a network". It has been working fine for the past nine months.Have had it less than a year, what is my next step?