@imjhoskins You may try reset the router, then upgrade immediately after initial setup. Do not restore an old backup after upgrade.
Or, you may try to restore “Access Control” only after upgrade. Other settings from an old backup may be incompatible. Send email to [email protected] if you still have trouble. Thanks!
Can you try to pick a specific channel instead of auto? Try different channels to see if that makes a difference. Also, you may try to change the channel width from 40MHz to 20MHz to see if that helps.