I am getting issue of 504 gateway timeout while sending sms frequently means some time it's working fine and sometime it's not working and it's getting problem in day time. Example : I m sending sms via scheduler so I have bunch of 200 sms and it's sending one by one so for the some sms is going but after some time one sms request is going and till the wait when 504 is not coming and it's getting too much time again after some time it's working fine, So I don't understand its application side problem or network side or sms vendor side.
The 504 HTTP status code indicates a Gateway Timeout error. As with all of the 5xx series status codes it represents an error in the server. This usually happens when a proxy server is unable to reach the underlying service. It is a problem on the SMS vendors side.