I noticed you're using GET for a lot of endpoints (authz, challenge, etc) that are now deprecated for use with GET requests. If you're actively working on new client code, you should definitely migrate to using POST-as-GET for those endpoints. The GETs will continue to work only until November 2019.
See the original announcement here:
And some additional discussion here:
In short, the only endpoints that will support GET after November 2019 are directory and newNonce (and newNonce should ideally use HEAD instead).