Yup, you can install free firmware on the node. The om5p-ac can run openwrt and it is supported hardware.
https://openwrt.org/toh/hwdata/open-mesh/open-mesh_om5p-ac
Some notes. If you install modern om5p-ac firmware it will lock down. Since you have old firmware, you should be able to flash it.
Once locked, you can flash only new firmware from datto and can't use ssh or serial.
The open source firmware does not have thermal protection so the node will not throttle itself if it overheats.
I just picked up two A62 APs to replace / test against my previous A60’s. The initial performance wasn’t good so I did a lot of adjusting today. I’m running beta firmware but like to play around at home, I have close to 50 open-mesh APs at customer sites.
Seems the 802.11r feature still doesn’t work, I disabled it, as I did with my A60’s. I saw one of their KB articles saying it’s still not ready for prime time.
I’m running 6.5 beta firmware which added 802.11k roaming “help.” Saw no benefit so turned it off for now, it’s a newly added feature with 6.5 beta so hopefully it will improve. I didn’t put too much time into testing though. I decided to turn off auto channel selection anyway, and you have to have that on if you want to use 802.11k.
6.5 lets you disable older / slower bandwidth technology, “lower legacy data rates” in the Radio config menu. I turned the legacy data rates off for both 2.4 and 5ghz. I don’t have any 2.4ghz devices so set SSID to 5ghz only anyway afterwards.
With auto channel config I was still getting lackluster speeds so I set the channels myself after scanning my area with inSSIDer Free from Metageek. https://www.metageek.com/products/inssider/
Then I enabled VHT80 channel width for both 5ghz radios. https://help.cloudtrax.com/hc/en-us/articles/115000257084?mobile_site=true
Speed is double for me now bouncing up and down between 350-550mbps.