Rocket Fails 3.20.3.1 - Kills LAN Port!

AREDN FW & HW Gurus Needed! I have encountered a really odd AREDN FW issue with a pair of Rocket M5 XM nodes. IF I flash with _anything_ later than AREDN 3.19.3.0, then the LAN port quits! Has anybody else encountered this type of problem? Or is there a fix? I have carefully dug through the AREDN Forum etc and have found nothing yet... Specifics and Background: - FYI - I have a deployable cache of two about dozen various UBNT & MikroTik nodes, including several more Rockets (M2 XM), and lots of success (hard earned, as usual!) in upgrading and flashing FW, since 3.16 days. - These two Rockets are both several years old, were bought used but have run fine for a year or two on previous FW versions. They are both M5 and XM. (Similar M2s do not have these problems.) - I am using simple WindowsXP with FireFox, simple PoE injector, and simple LAN cables. No switch (dumb or smarty). This has been working perfectly for all nodes, including these two. - I can successfully access both Rockets with TFTP and (apparently!) load almost anything, including UBNT XM factory and AREDN factory. - The problem was originally encountered when trying to do a simple AREDN FW upgrade from NB 1138 (was working fine!) right to NB 1755. - After rebooting, we encountered NO LAN data (PC indicated cable disconnected!) and also no LAN lite (second LED)! - So, I started standard diagnostic procedures, including retrograde loading and testing, various FW as far back as 2.16.3, assorted NB, both AREDN factory and upgrade, even UBNT XM 5.5 & 5,6 factory, etc. (Very complex and depressing details upon request!). - Confirmed Results: The Rockets will function correctly up to FW 3.19.3.0, BUT nothing later! --- Evidently we can discount any _HW_ failure, since the behavior is dependent on the FW version variable only. --- Also, I feel we can likely discount the more traditional causes, such as phases of the moon, sunspots, required chicken sacrifice, et al.... ;-) Sooooo, what are the possibilities? - Was something in the upgrade from 3.19.3.0 to 3.20.3.0/.1 _changed_ to kill the LAN ports? --- Perhaps a LAN port chip _driver_ change, or error? - Is something unique to the Rocket _M5_ XM that is _different_ from similar Rocket _M2_ XM nodes? --- I understand that they have identical main boards, with identical LAN elements, and only vary in the RF elements? - Anybody have a better idea? AREDN FW Guru Clues Please?? Also, one of these is bolted to my Trusty Big Stick deployable system (RocketM2 & RocketM5 on Altelix high gain dual band OMNI, plus NanoStation5 link.) But fortunately the other is loose and could be shipped for exam if needed. Thanks! Gene :) N3EV@arrl.net (Posting a Reply is great. AND Please feel free to buzz me directly, too?)