Hi @pariv_0352,
Thanks for clarifying; looking closer, ProGet requires that X-Forwarded-Host is simply a hostname. You're right, there is no "standard" for this, but that's what ProGet does for the time being.. and if the input is invalid, then you get the error you'll see.
I would change your reverse-proxy header configuration to:
X-Forwarded-Host: www.testdomain.com
X-Forwarded-Port: 82
Hope that helps,
Steve