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I'm getting reports from users that clicking a link gives them Page Not Found.
- These are anonymous users.
- Page caching is turned on (but not aggressive)
- I log in, the page works. I log out, the page does not work.
- Three reports of unrelated pages in the past week (but all were different node types)
- Clearing All Caches fixes it.
- I could be wrong about this (because I didn't think to check until after I cleared caches), but I think it's returning error 406 in Recent Log Entries.
How can I begin to troubleshoot this?