2592011 - Larger attachments can't be uploaded through SMP and the process throws error code 504 (Gateway timeout)

When a mobile client tries to upload a larger attachment (image, pdf, video etc.) to the SAP backend through SMP, it receives error code 504 Gateway timeout and the below error messages:

TRACE#com.sap.mobile.platform.server.notifications.async.impl.DispatchRunnables-push-dispatcher-1#Skipping dispatch for tenant <tenantId>. Delay not yet reached
WARN#com.sap.mobile.platform.server.proxy.core.handler.DirectProxy#<AppID>#RequestResponse#An IOException occured, assume it can be retried
com.sap.mobile.platform.server.proxy.connectivity.core.exception.ConnectivityException: <HostName>:<Port>failed to respond
...
INFO#com.sap.mobile.platform.server.proxy.core.handler.DirectProxy#ODP request failed: method: POST, url: <URL>, status: -1, duration: 1562 ms, exception: NoHttpResponseException=<HostName>:<Port> failed to respond.

SAP Mobile Platform (SMP) 3.0 OData Runtime

jpg, pdf, gif, doc, occurred, txt, mp4, mp3, png, jpeg, docx, maxRequestEntityAllowed, upload_max_filesize, DoS attack , KBA , MOB-ONP-ODP , SAP Mobile On Premise Proxy Services , Problem