No issues updating using Check for Updates on Winbox on CR326-24G-2S+, and 3 hAP ac2.

Essentially, T-Mobile’s only offering that would match is the home internet plan, but they only allow certain equipment (their equipment), MT not included. Your only option would be to order a bring your own device kit, so it just includes a sim. This might require you to say you will be using other...

Disable CAPS under the CAPS button on the AP wireless interface. Then try your mesh setup. Once CAPS mode is enabled on a device, most selections you’ve made in the wireless interfaces category will not be active.