I recently had a lengthy battle with a domain forest. Apparently, queries on the forest do not support paging. As part of my troubleshooting, I did implement the option to set a maximum search size for when you cannot page. It is another extension method on the configuration. I had to introduce a bunch of variables throughout and expose a protected property to be able to access the property 'SizeLimit' in DirectoryQueryProvider.Execute.
I recently had a lengthy battle with a domain forest. Apparently, queries on the forest do not support paging. As part of my troubleshooting, I did implement the option to set a maximum search size for when you cannot page. It is another extension method on the configuration. I had to introduce a bunch of variables throughout and expose a protected property to be able to access the property 'SizeLimit' in DirectoryQueryProvider.Execute.
My implementation can be seen here
Any chance you'd consider mainlining that, or maybe you have a better approach.