Unable to connect. Error proxy server got bad address from remote server (verify the server is running) Status code 504

[KennethLynk1]

When trying to connect to the USDA public server (http://gis.apfo.usda.gov/arcgis/services) I get the message: Unable to connect. Error proxy server got bad address from remote server (verify the server is running) Status code 504.  Tried several time over.

Trying to connect through ArcMap 10.5.

[JayantaPoddar]

Try this URL

https://gis.apfo.usda.gov/arcgis/rest/services 

[JoshuaBixby · Accepted solution]

Or even https://gis.apfo.usda.gov/arcgis/services , the OP just needs to use HTTPS instead of HTTP since most federal government sites are now enforcing SSL/TLS.