Comment 121 for bug 1297849

Had the same problem on 15.04. I manually add the route but in 15.04 NM seems to be changed and no longer works. What I did instead is to add the manual route normally but changed the gateway (routes -> gateway) to 0.0.0.0 , that worked for me. I hope it can help you too. Additionally, you can try change the route to something like: sudo ip r a 10.0.0.0/8 dev ppp0 - this also worked for me.