Can no longer reset modem from iPhone app

Let me start off by saying that I have been the victim of MULTIPLE momentary service interruptions lasting 5-10 minutes.  It seems that at least 2-3 times a week I have this issue, and one of those days is almost ALWAYS Sundays.  When this occurs, I usually switch my iPhone over to mobile data, and access the Cox app to troubleshoot my modem.  In there, I use the button to reset the modem.   It used to be that it would perform as advertised  However, for the last 2 months or so, I keep getting an error that says "Cannot Reset Modem", and gives me the option of either contacting customer service or retrying (the latter never works).  How come this functions no longer works?  It is very frustrating.