Based on your method hotspots it's clear that there is a network IO involved. I'm not sure how many stack-traces were included in this hotspot analysis - if the number is too low, it won't be much valuable for getting any conclusions. Typically such situations as you have are in cases where network latencies or retransmissions happen (more likely) or a high volume of data is transferred (less likely in this case).
To visualise it in the service flow, you would normally have to define a customer service. Since this is a NET system class, this is unfortunately not possible.
Closest visualisation I can think of would be the custom service metric that will measure the network time for those particular services and requests. But it will be calculated from the service itself. Not measuring just DownloadMetadata.
What I am trying to find out is the following:
I found have method hotspot for this particular problem reported and now how to get the endpoint location that is consuming the Network IO.
I am drilling down to DownloadMetadata() and I cannot figure out what is being called.
On the other side, since it's a HTTP request issued from the code, what other services or request to unmonitored hosts are called from this purepath or service? It will likely be one of those URLs.