Reposting - Any suggestions on resolving a Weak WiFi signal?

We live in a ranch and have never had a problem with the WiFi reach in our bedroom, but now it's constantly dropping out on our devices.   We had a power outage last week, could something have happened to the modem?  I have restarted the modem but it hasn't helped.  How do I know when I need a new Xfinity modem?  Do I now need pod extenders for some reason?