UCD invalid or channel unusable

My internet connection will fail several times in a day, then stay connected for 1-3 days and then the cycle repeats.   Most of the outages are short lived (3-10 minutes).  The modem lights appear to show a good connection during the outages.  When I look at my modem's event log, I see there are Critical Events that correspond with these outages.  They are always UCD invalid or channel unusable.  I am paying way too much for this service to have outages that are this frequent.  What are the steps required to troubleshoot and fix this.  I believe that it will probably require a technician to visit my home but am willing to try any recommended steps before requesting a visit.  Note that I am using Motorola MB8611 modem which is connected to a mesh router wifi system.  The outages affect laptop, phone and streaming.  Wouldn't you know it? When I tried to submit this post, my internet experienced an outage.  It resumed after about 5 minutes.