I'm treading lightly in an attempt to not brick the device.
I found the following post and it suggests that to upgrade from 19.xx to a new firmware that a forced sysupgrade of a _____________linksys_wrt1900ac-v1-squashfs-factory.img can been done vi the the GUI.
Is this what you were recommending to do to overcome the size issue?
Yes, WiFi functionality is import. What firmware should I use?
Thanks for your input and guidance.