Make sure the time is set correctly.
no dog splash is dead (yet still installable), use opennds.
On 4 MB flash, there isn't space to install anything at runtime. You will need to use Image Builder or Firmware Selector to make a custom ROM with what you need-- and take out some standard packages e.g. luci and opkg to make space.
As I said this is a headache and you probably want to first get opennds running on some sort of test router that is not limited by memory before considering deployment to your WR940(s).