Re-program Quectel modem after factory reset and firmware upgrade

Does any know the set of AT commands that can re-program the Quectel modems after factory reset and firmware upgrade? I have an RM500QAE and an EM16G. I have performed firmware upgrades and full factory resets on both modems but I am having issues with my internet speeds now. I would like to re-program for t-mobile LTE internet. Pease help as I use these for my business. Also, I should report that the 5g modem was getting over 100 mb download speeds and now it is only getting 10mb after reset. Thank you