Edit: Got the error again. Either WTM has problems or AW doesn't handle the error/redirect.
GET http://www.whattomine.com/coins.json
HTTP/1.1 308 Permanent Redirect
Date: Fri, 18 Jan 2019 10:15:11 GMT
Content-Type: text/html
Connection: close
Set-Cookie: __cfduid=d38d33f7cf5c410085334c9647cd6b1121547806511; expires=Sat, 18-Jan-20 10:15:11 GMT; path=/; domain=.whattomine.com; HttpOnly
Location: https://www.whattomine.com/coins.json
CF-Cache-Status: MISS
Vary: Accept-Encoding
Server: cloudflare
CF-RAY: 49b04c8986ee5b5d-HEL
308 Permanent Redirect
308 Permanent Redirect
nginx/1.15.3
Could you please try again? The problem was that http got redirected to https and json consumers not always handle that.
Good idea to also switch to https if possible

@patrike please force all communications to wtm to use https.