xFi pods seem faulty

I installed 3 xFi pods about a year ago.  Since then, connectivity has been good and speeds have been blazing. Until recently.  Some devices are still getting blazing speeds (> 400 MB/sec) but intermittently in some parts of the house, especially near xFi pods, speed has been inconsistent.  Sometimes excellent, sometimes very slow (2 MB/sec) or not at all.  I replaced the modem/router and did other troubleshooting and finally decided it must be the xFi pods.  I unplugged all the pods and immediately speeds on all my devices increased.  Couldn't find good info on website on how to troubleshoot pods.  Should I try to re-install?  or take them back to the store?  or ??