When I try to save a large set of adds/edit to a Map Service applyEdits endpoint, if the POST body reaches a certain size, the operation will fail, with a bogus error:
"Could not access any server machines. Please contact your system administrator."
But If I cut back on the number of edits, It will save. I haven't found the threshold yet, but an 8 MB post body will save, and a 17MB POST will throw this error. The service also has a SDE connection to an Oracle enterprise DB.