As if any provider (leaving open which kind is actually meant - the one (re)selling the RM551E-GL module itself or an ISP?) would provide such profound detailed information. Often enough, they don’t even understand the inquiry and ask for the customer ID. 
@silvia what’s the reason for all that secrecy fuss by the way in general? From lists of supported bands to firmware updates - it’s always that conspirative “mailing such stuff directly to users at best” but no public, simply accessible download area on the Quectel website.
Do we have to make lives make even harder for all of us? After all, your products - despite being great from a technical standpoint - aren’t exactly free from bugs or weird implementation decisions such as the impossibility now to set the generic MAC address for the bridge mode on the RM551E-GL.
Wouldn’t you actually benefit from a broader community which plays the unpaid alpha tester at the end of the day?