Microsoft have been ramping up the security of their endpoints and its getting more complicated to get old devices to continue working.
TLS1.2 now required by default
My device is TLS 1.1 though, and i dont have a way to update the firmware to support TLS1.2 or TLS1.3
So Microsoft have a legacy TLS 1.1 endpoint endpoint which you can enable
Once enabled, you have to configured your devices to use smtp-legacy.office365.com
Microsoft is phasing out SMTP-AUTH in favour of OAUTH
SMTP-AUTH or basic auth is getting phased out. But similarly, devices dont support OAUTH yet.
So, you have to reenable SMTP-AUTH
You have to enable it in exchange in screen shot above, but ALSO you need to disable default security in azure.
Use app password since you have 2fa enabled
Finally since you have 2fa enabled, you will need to create an app password for you device to use.