This is the most likely cause of the issue because firewall rules can block or allow traffic based on source, destination, port, protocol, or other criteria. If the firewall rules are not configured properly, they can prevent remote users from accessing the cloud application server, while allowing on-site users to access it. References:
https://docs.microsoft.com/en-us/azure/virtual-network/security-overview

A rescan on the server's RAID controller is a possible troubleshooting step to detect the existing RAID configurations on the connected storage arrays. A firmware upgrade may cause the RAID controller to lose the RAID metadata or settings, and a rescan may restore them. A rescan is preferable to restoring the default RAID configuration, as the latter may erase the existing data on the arrays. Power cycling the storage arrays or booting the OS into recovery mode may not help if the RAID controller does not recognize the RAID sets.

This is the most secure method to access servers located in remote branch offices because MFA stands for multi-factor authentication, which requires users to provide more than one piece of evidence to prove their identity. An out-of-band solution means that one of the factors is delivered through a separate channel, such as a phone call, a text message, or an email. This adds an extra layer of security and prevents unauthorized access even if a password is compromised.References:https://docs.microsoft.com/en-us/azure/active-directory
/authentication/concept-mfa-howitworks