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Is anyone else experiencing random times where the CSS styling disappears on any SO site?

Occasionally when browsing Stack Overflow and its counterparts the CSS would fail to download, and the whole page would be left a unstyled mess.

When loading the present stylesheet (at the time of writing):


It will either work or return a 404 error. Both outcomes occur with roughly the same consistency, regardless of which browser I use to connect.

Whilst a few refreshes has thus far fixed the problem, I wasn't sure whether it was just a problem on my end or a bug other people have been experiencing.

  • Nope. Haven't seen that unless it was a forced load cancel.
    – random
    Commented Nov 12, 2009 at 13:11
  • Happens from time to time. Which means this is a dupe (but I'm too lazy to search it now). Keep hitting F5 (or Ctrl+F5 for the sake of variety). Commented Nov 12, 2009 at 13:14
  • Ah, someone found it for me: meta.stackexchange.com/questions/20068/… Commented Nov 12, 2009 at 13:36

1 Answer 1


I certainly haven't seen it that often but I have seen it. There can be a few explanations.

Since we have to assume the server is up either the server isn't getting the request or we're not getting the response. This could be happening because the server is overlaoded or the network connection to it is. It could also be happening on our end. Most home routers use some form of NAT (network address translation). Depending on your router, it will support a given number of NAT sessions at once. It might be 512 or less. Better routers will have 1500+. Enterprise grade routers may have 4k+.

When you run out of NAT sessions it can act like a bad network. Randomly dropped packets, etc. There are a couple of reasons that often explain NAT session exhaustion:

  1. You're simply using too many connections. BitTorrent clients are particularly susceptible to this. You might be attempting 100-300 connections per second per torrent; or

  2. The timeout value on your router is simply too high so connections aren't being made available quick enough.

Or you might have a few computers on your home network (or even corporate network) that are simply trying to do more things than your hardware (or how you've configured it) can handle it.

My own router I bought because it supports 1500 and I was hitting that on occasion. I changed my settings (in both the router and on utorrent) and it rarely gets above 300 now.

  • A good point. However, on failure it loads a HTML error page from the server, which I suppose would be indicative of a server problem rather than a hardware problem. Commented Nov 12, 2009 at 13:28
  • So it definitely is returning a 404? Ok, that is different. It could be the server. It could also be a proxy (if you're using one; and you don't necessarily have to configure one to be using one). I'm also wondering if a firewall could produce this result?
    – cletus
    Commented Nov 12, 2009 at 13:39

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