Top Tier Internet Service Still Getting Inconsistent Service

About a week ago new dead spots appeared suddenly in our home wifi network.  We have an xFi gateway and 3 1st gen xFi pods.  For most of the last 2 years, this setup has operated without problems.  More recently (last 2 mos.) we have had numerous intermittent internet connection problems in certain rooms upstairs.  The xFi app reports that all our pods are working and have strong strong wifi signals, and all our devices are also connected (even when they clearly aren't) and have strong signals as well.  We also paid extra for a technician visit. He conducted an analysis of the connection. Is the problem related to outdated gateway and pods? We pay too much for our internet service, so this is very frustrated, please help!!!