I'm afraid there's not any further configuration. This will happen on any server, physical or virtual, when the SQL Server cannot be contacted. It's usually related to network connections, or the SQL Server is just totally bogged down from other things. See if rebooting fixed it, that will often help.

Please review KB#1161 for instructions on how to update this.

I would also try to upgrade your new server to 4.7.6 as well, because I really can't think of anything in the ProGet software that would yield this behavior. The file's bytes are simply written to disk as they are received using streams and async methods. Moreover, we test with large packages and have a lot of users who have large packages, and none have reported issues.

Yes, that's precisely what it would be; an ATOM feed for private galleries that you can push extensions to. I think only MyGet supports it now, so we will look to them for how they handle pushing, so it can be consistent. Most of our enterprise customers wanted to create a workflow like they do with NuGet.org, with only certan public packages in the feed, etc. THat is, they didn't have custom extensions, they only wanted to restrict or cache public extensions for their developers.