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