@Cooperttw - more information is needed. I assume "the bars" are the 3G indicator. From my blog (link is in my sig line), "A flashing green 3G light indicates a failed update, a hardware failure, or something is blocking access to the AT&T Mobility Servers."
Which model of MicroCell do you have, white or black?
Have you had any updates to your equipment lately (gateway, router, or modem)?
Who is your ISP?
AT&T discontinued sales of the MicroCell at the end of 2017 because the MicroCell has reached its EOL. Service will continue, with probably declining support, until AT&T transitions away from their 3G network. The sunset date is around Feb. 2022. At that point in time, the MicroCell service itself will be discontinued. What AT&T and us recommend now is WiFi-C (WiFi Calling) if your phone is capable. Call quality and reliability is much better.
Award for Community Excellence 2019 Achiever* *I am not an AT&T employee, and the views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.