make a note of the Instant 8.12.x firmware you are running in the office.
Then download the firmware from the support portal and upgrade your AP-303H in an isolated vlan before adding it to your other cluster.

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Original Message:
Sent: Jul 12, 2024 12:34 AM
From: thyk123
Subject: AP 303H update from 6.5 to 8.12 in 2024
Hi, thank you so much for the reply!
I see, so I should register with the office email. I will test it soon
Right now, AP operates under a Virtual Controller.
Original Message:
Sent: Jul 12, 2024 12:04 AM
From: schmelzle
Subject: AP 303H update from 6.5 to 8.12 in 2024
You can create an account using your work email address (don't use gmail, etc) on https://networkingsupport.hpe.com to access downloads.
Is your 303H currently operating as a campus AP (CAP) tunneled to a controller or is it running as a standalone Instant AP (IAP)?