The 2.8.1 firmware is available on the web dashboard to upgrade the C5x PTP. However, after installing this firmware, the units will pass traffic, but won’t communicate with the web dashboard. I’m currently in the process of rolling them back to 220.127.116.11.
So, if the 2.8.1 firmware isn’t for the C5x PTP, then going to Update Firmware in the web dashboard shouldn’t offer it. If it is for the C5x PTP, then there’s a problem with it. Either way, there’s something that needs fixed.
Additional info: Rolling back to 18.104.22.168 did allow them to communicate with the Mimosa web Dashboard.