When trying to refresh the access token when it expires, had an error:
Access Denied You don't have permission to access "http://api.sonos.com/auth/oauth/v2/access" on this server. Reference #18.cc5e0e17.1539959683.3844201.
Using request from Sonos API reference: https://developer.sonos.com/reference/authorization-api/refresh-token/
Authorization the same as in "Create token" request, and it works. And refresh token is from responce to "Create token" request
It looks like you've got the wrong URL. The path should be /login/v3/oauth/access. We did have a mistake in our documentation which likely led to your error.