authentication issue with web API

Dear Team,

Hope you all are doing well and Happy NEw Year 2020 in advance.

I am new to web API objects in APPIAN and trying to develop one. Goal is to make data in one of my data store entity available to third party system outside APPIAN.

Here is what I did : Created a web API with GET 'Query Data Store' template and passed my data store entity in it. Created a http connected system with basic authentication usernam/password combo. Created third party credntials as well (not sure if this is required). Created integration object with basic authentication.

Now when I am hitting the URL in same session of chrome or test the API within API, I get expected data in JSON format 200 Ok. Eveything looks fine here but as soon as access the api URL from other machin or in other session of IE, I get following error :

{"resource":"\/suite\/webapi\/rpttr","error":"APNX-1-4187-000","message":"Authentication failed. Please check your credentials and try again.","title":"An Error Has Occurred"}

and when I am testing integration object : I get following error
"Appian was not able to authenticate with the username and password you provided. This request requires Basic authentication."

I know its a naive question but any help to sort this would be appreciated.

Thanks.