It appears that there's a bug with Android which prevents IPSec VPN connections. There is a fix, but it requires editing ipsec.conf on the server:

https://code.google.com/p/android/issues/detail?id=196939 (post 35):

Is there a way I can edit ipsec.conf on the router so that I can add "sha2-truncbug=yes"? I tried the console, but there doesn't appear to be a way to edit files.

You didn't say what router... but I doubt you can as the Vigor is an embedded device (the DrayOS version) and doesn't have specific config files. DrayTek are unlikely to add a 'feature' to get around a temporary bug in another device I'd guess.