If the Eagle auto-router refuse to work at all or less than 100% done, there must be too crowd area which auto-router can not pass all the wires between components. In such cases, I would move some components to where less crowd area and try it again until the progress is done all the way to 100%.
Personally, I love auto-router of Eagle. I have used the auto-router function since the version 5.8 or 9, quite recent versions though, and found it worked great. I have had problems with PCBs with SMDs, but for the through-hole components based PCBs, I would strongly like to recommend to try the auto-router.