I got another D-Link DIR-600. This time a B2E...
It shows 14.4MB (even though it is supposed to only have 4MB) available in the "Software-Tab" and after a reboot it lost all settings and installed packages.
What could be the reason??
Installing OpenWRT worked flawless, so if this thing really has 16MB, I'd like to build the newest OpenWRT for it, including some packages like the (big) wpad, etc.!
The flash is overfull so it mounted overlay on the RAM disk, which has a size of about half of the RAM. Since the filesystem is RAM, everything you configure or install gets erased on a reboot.
32MB RAM is a severe problem running new versions, no matter how much flash you have. RAM upgrade is not possible as the RT3050 supports a maximum of 32MB.