Odd new Error Message

For some reason now, when I attempt to go to one particular site I receive an error message: Error 502: failed to receive headers in response . This was brought up to me by a customer and this is only happening to this site when attempting to access it thru my Mikrotik machine. I have not changed my set-up in months and apparently this just started.

Mikrotik version 2.8.28

Any suggestions of what this could be from.

Jeff Kratka