Recommendations for freezer temperature monitors/alarms

I just got my first (extra) freezer and have a 1/4 of beef coming. I am worried about something going wrong with my freezer and not knowing about it until it is too late.

Does anyone have any experience with a monitor that will let me check my freezer temp and alarm me (preferably on my phone) if it gets warm? I have seen some on Amazon but they seem to have mixed reviews and connectivity issues.