PayPal Redirect issue

1 week ago
I am guessing paypal changed something a few weeks ago.  my paypal orders are no longer being marked as paid and customers are receiving this error.  

nop3.6 using Payments.PayPalStandard

Server Error in '/' Application.
The request was aborted: Could not create SSL/TLS secure channel.

my SSL is good through July.  

where do i find the URL that paypal redirects to?
any other ideas as to where to look for resolving this?

thank you in advance
1 week ago
Before diving in too deep, check your server to see if it still supports TLS 1.0, 1.1 or anything less like SSL:  https://www.ssllabs.com/ssltest/

PayPal requires TLS 1.2 or higher, and will refuse connections if they detect those insecure protocols enabled on your server:
https://developer.paypal.com/docs/api/info-security-guidelines/#usetls12