EBS Punchout - ERR_SSL_PROTOCOL_ERROR

We are currently running EBS 12.2.5, and have been able to punchout to a supplier (Dell) for a long time now. However, it has always been with a workaround, either by using IE or recently using Edge in IE mode.

It appears Dell changes the postback URL that we send them from http to https. When using IE or Edge in IE mode the browser would automatically change it back to http when posting back to EBS, but now the Dell site is not allowing Edge in IE mode.

Here is what we send:

<BrowserFormPost>

            <URL>http://server.domain/OA_HTML/OA.jsp?OAFunc=ICX_CAT_PUNCHOUT_CALLBACK&amp;OAHP=ICX_POR_HOMEPAGE_MENU&amp;OASF=ICX_CAT_PUNCHOUT_CALLBACK&amp;transactionid=1666318854&amp;operationkey=b4df3f94d6f83d1b</URL>