Create backup of Aerohive AP121 and restore original FW

I have 7 accesspoint, Aerohive (HiveOS, now Extreme Networking) with OpenWRT and I would like to revert a few back to stock.

I have 1 AP with the original firmware but cannot find the firmware as a download anymore.
The old AeroHive website has gone offline and so are the (depricated) FW files.

Is it possible to create a backup from the original AP and if so, how would I do that?

The upgrade procedure for this device is achieved with the following commands:
tftpboot 0x81000000 openwrt-19.07.4-ar71xx-nand-hiveap-121-squashfs-factory.bin

Now, erase both stock kernels and rootfs partitions (they will be replaced with a single kernel and a larger UBI partition) and flash OpenWrt:

nand erase 0x800000 0x7400000
nand write 0x81000000 0x800000 0x${filesize}

The remaining AP has HiveOS 6.5r14

I need the original firmware , if you have it pls give me it.