It's cgminer version 4.7.1
Is there a newer openwrt opkg version available?
Well that would explain the breakage then. No idea about opkg versions, but additionally I don't believe any of the antminer forks remotely tried to stay in sync with the master cgminer.
Maybe you got me wrong: I mean whether there is a newer binary version of cgminer available for the openwrt platform, ie. as a opkg-package.
And as I said, I have no idea about opkg packages. I have nothing to do with their maintenance.