So, further testing shows that this only happens if I have 2.4ghz enabled on the SSID that I enable MLO on.  The EAP783 is supposed to support MLO for 2.4ghz + 5ghz + 6ghz, but it seems I crash if I include 2.4ghz but am functional with only 5ghz and 6ghz (though needs longer term testing, but stable for at least a few hours now).

I would really like 2.4ghz included in my MLO SSID as there are some corners of the home and areas outside where 5ghz and 6ghz don't reach well and I'd rather not rely on the iPhone to switch SSIDs as it's unlikely to switch back to the MLO SSID later.  Definitely better if MLO includes all three and negotiation of which channels to use based on strength works properly.

Hi  @jmccaskey 

Thank you so much for taking the time to post the issue on TP-Link community!
To better assist you, I've created a support ticket via your registered email address, and escalated it to our support engineer to look into the issue. The ticket ID is TKID240957496, please check your email box and ensure the support email is well received. Thanks!
Once the issue is addressed or resolved, welcome to update this topic thread with your solution to help others who may encounter the same issue as you did.
Many thanks for your great cooperation and patience!

  @jmccaskey did you end up finding a solution for this? (Other than deactivating the 2.4 band for MLO)

  @PavelF I haven't had a solution yet, but support has been engaged and they suggest this issue will be fixed with a new firmware update (they didn't have a beta to share yet) hopefully within the next month.

  @jmccaskey Thanks for the update.

  @Vincent-TP 

Is there an ETA for a fix?

  @Vincent-TP 

Will the beta be available via the controller interface soon or can I manually download it from somewhere?

Hi  @W38122077 

I have emailed the beta to your email. Please try find out it from your email inbox with the case ID TKID241140172.

  @Vincent-TP 

Thanks.  I tried it out after the other troubleshooting on the other thread and something is bad with that .19 beta firmware.  Its something to do with the trunking option (I suspect) and spanning tree as I got a lot of STP topology change notices and then my LAN went down and I had to start rebooting stuff so I could get to a point where I could revert it.