Hey,
Are you still having issues with this?
If you navigate to the url:
{instance URL}/Api
(ie: www.crm.com/Api)
What do you see?
I believe, if the API is working, you should see something similar to this:
If not, then it would be worth re-visiting the setup of the API.
One thing I’ve encountered previously was that the “mod_rewrite” apache module wasn’t enabled:
https://community.suitecrm.com/t/request-to-api-return-404-error/65657/13
Can you check if this is enabled on your client server?
Otherwise, could you pass over the URL/Body format that you are using to send the Auth request?
Would be good to get a look at that too 