For Digi Cell Extenders - 6300, 6310 and EX15 devices should not be affected. For more information on Digi devices and ongoing updates, please refer to the following knowledgebase article: AT&T 3G Network Sunset February 2022
Useful site links:
U115 Setup - https://u115start.com/
ARMT Users Guide - https://accelerated.screenstepslive.com/s/att/m/ARMT_User_Guide
Please report any issues via the Feedback link at the bottom of the page.