I've just update the firmware of my netgear DGN3500, all is working fine, but can't install package. In Luci when i try to update list i've the message :
"Waiting for the opkg update command to complete…"
but never ending ...
yes i can ping, every diagnostic works. I upgraded from chaos_calmer 15.05, and i check keep settings. Like i said, all works, i'm using it, but impossible to use wget and update package.
When upgrading from one major version to another it is highly recommended not to keep settings. In your case I'd say it's the root cause.
Take a configuration backup first. Then reset the router to defaults. Finally start reconfiguring the router manually using the backup files as a reference only.