Something went wrong failed to fetch

on https://appacademy-online.herokuapp.com/methods-quiz

player.vimeo.com/video/205955254/config/request?session=f3183d93b0266937e66…54&signature=814d01c3c04f2b4742e940ac0e8ab22a&time=1493076254&expires=9164 Failed to load resource: net::ERR_NAME_RESOLUTION_FAILED
f.vimeocdn.com/p/2.55.6/js/player.js:2 Uncaught (in promise) Error: The request failed.
player.vimeo.com/video/205955254/config/request?session=f3183d93b0266937e66…54&signature=814d01c3c04f2b4742e940ac0e8ab22a&time=1493076254&expires=9164 Failed to load resource: net::ERR_NAME_RESOLUTION_FAILED
f.vimeocdn.com/p/2.55.6/js/player.js:2 Uncaught (in promise) Error: The request failed.
player.vimeo.com/video/204978291/config/request?session=641f227052df213ec7e…70&signature=a750659a3b2cad3082ffb9e8b5a06c39&time=1493256170&expires=4676 Failed to load resource: net::ERR_NAME_RESOLUTION_FAILED
f.vimeocdn.com/p/2.55.7/js/player.js:2 Uncaught (in promise) Error: The request failed.
player.vimeo.com/video/204978291/config/request?session=641f227052df213ec7e…70&signature=a750659a3b2cad3082ffb9e8b5a06c39&time=1493256170&expires=4676 Failed to load resource: net::ERR_NAME_RESOLUTION_FAILED
f.vimeocdn.com/p/2.55.7/js/player.js:2 Uncaught (in promise) Error: The request failed.
player.vimeo.com/video/204978291/config/request?session=838c16331ad5815e59b…77&signature=688deaa05bd8bb7f547cf0088d6d7606&time=1493333977&expires=4676 Failed to load resource: net::ERR_NAME_RESOLUTION_FAILED
f.vimeocdn.com/p/2.56.0/js/player.js:2 Uncaught (in promise) Error: The request failed.
player.vimeo.com/video/204978291/config/request?session=838c16331ad5815e59b…77&signature=688deaa05bd8bb7f547cf0088d6d7606&time=1493333977&expires=4676 Failed to load resource: net::ERR_NAME_RESOLUTION_FAILED
f.vimeocdn.com/p/2.56.0/js/player.js:2 Uncaught (in promise) Error: The request failed.
api/user_tasks/14715/submit Failed to load resource: the server responded with a status of 412 (Precondition Failed)
api/user_tasks/14715/submit Failed to load resource: net::ERR_TIMED_OUT
application-6902d6e….js:19 POST https://appacademy-online.herokuapp.com/api/user_tasks/14715/submit net::ERR_TIMED_OUT
(anonymous) @ application-6902d6e….js:19
(anonymous) @ application-6902d6e….js:23
submit @ application-6902d6e….js:21
onClick @ application-6902d6e….js:21
l @ application-6902d6e….js:21
e @ application-6902d6e….js:13
a @ application-6902d6e….js:13
s @ application-6902d6e….js:13
h @ application-6902d6e….js:13
m @ application-6902d6e….js:13
e @ application-6902d6e….js:13
processEventQueue @ application-6902d6e….js:13
r @ application-6902d6e….js:14
handleTopLevel @ application-6902d6e….js:14
o @ application-6902d6e….js:15
perform @ application-6902d6e….js:13
batchedUpdates @ application-6902d6e….js:15
o @ application-6902d6e….js:13
dispatchEvent @ application-6902d6e….js:15
collect Failed to load resource: net::ERR_TIMED_OUT
www.google-analytics.com/collect?v=1&_v=j52&a=1014378327&t=timing&_s=118&dl…riculum&cd2=70748be3-bb90-4e43-8f43-66db18ba60d0&did=i5iSjo&z=1312730675:1 GET https://www.google-analytics.com/collect?v=1&v=j52&a=1014378327&t=timing&…urriculum&cd2=70748be3-bb90-4e43-8f43-66db18ba60d0&did=i5iSjo&z=1312730675 net::ERR_TIMED_OUT

from javascript console.