I have an online store (web Asp.Net application in c# with Sql Server Express) integrated with PayPal. I used the code for pdt given at the following link https://github.com/paypal/pdt-code-samples/blob/master/paypal_pdt.cs. Everything worked perfectly during development using sendbox, but on the server, after the payment on PayPal by redirecting to the page on the site, the connection drops and generates an error on the line of code StreamWriter streamOut = new StreamWriter(req.GetRequestStream(), System.Text.Encoding.ASCII).
I tried everything, but I still can't understand what is wrong. Can you help me? Is there any problem from you with my site?
TLS 1.2 is configured correctly using Qualsys SSL Labs (the site has an A for overall rating). Thank you.