We dont have option to upgrade server from GUI, we can upgrade only from AMPCLI.
Online upgrade: (server have internet access)
Login to AMPCLI and choose option 7 (upgrade) > option 1 (Upgrade Airwave Managment Platform)> Provide version details and hit enter , it will prompt two option aruba or MNP HPE credentails to use download the software automatically, choose any option and hit enter it will automatically download software and upgrade.
Offline:
Download upgrade package from support.arubanetworks.com , once you have copy upload to Airwave using AMPCLI option Upload File.
Note: You need external SCP server to copy file to Airwave, provide patch to file to upload the package.
Once files is uploaded, go to upgrade option 7 and provide version , it will use manually uploaded packge to upgrade, it wont prompt again credentails to donwload the file.