I have three sites all running on my own server. Two passed fine, but one has gotten this error about 4 times:
Network unreachable: Network unreachable
We encountered an error while trying to access your Sitemap. Please ensure your Sitemap follows our guidelines and can be accessed at the location you provided and then resubmit.
The sitemap can be reached fine. I don't understand. This is the URL:
[external links are visible to admins only]
I just thought of something that may be relevant. I am using a service to block IPs from certain countries. I guess Google isn't doing this from the United States. I have removed the blocking and getting tested again.