People seem to be missing that FTP and MQTT are generally insecure protocols. I think FTP is probably the bigger issue than MQTT. This kind of stuff is common in home IOT networks but would never pass security audit on a corporate network.
Bambu is growing up, serving more corporations beyond the hobby community, and probably has been asked to beef their security up to make it easier to deploy their printers securely.
Moving to Mutual TLS via a controlled client like Bambu Connect is a pretty industry standard approach to secure, authenticated communication that doesn't require an internet connection, it is done with digital signatures offline.... and thus it can be done over a LAN. It's how many web APIs inside a corporate network are secured. It's how web browsers are secured. Microsoft, Mozilla, Google, Apple, etc. all send you revised certs/keys regularly in your OS or browser patches. Client authentication via x.509 cert signature or subject verification isn't super common on the public web but it does happen a lot with mobile apps or thick client apps, or some websites, e.g. SAP's many websites often use it to verify you're a customer.
Bambu is growing up, serving more corporations beyond the hobby community, and probably has been asked to beef their security up to make it easier to deploy their printers securely.
Moving to Mutual TLS via a controlled client like Bambu Connect is a pretty industry standard approach to secure, authenticated communication that doesn't require an internet connection, it is done with digital signatures offline.... and thus it can be done over a LAN. It's how many web APIs inside a corporate network are secured. It's how web browsers are secured. Microsoft, Mozilla, Google, Apple, etc. all send you revised certs/keys regularly in your OS or browser patches. Client authentication via x.509 cert signature or subject verification isn't super common on the public web but it does happen a lot with mobile apps or thick client apps, or some websites, e.g. SAP's many websites often use it to verify you're a customer.