Here is what I have found. When the user is behind a hotspot and they go to http://www.speedguide.net:8080/
their MTU is 1500, and their MSS is 1460. When the user is bypassed from the hotspot, their MTU is 1480 and 1440.
Once again, the problem only occurs when the user is behind the hotspot. No mangle rules are enabled at this time.
The transparent-proxy option is currently set to "off." One more note, is that this problem is occurring on all hotspot routers that are upstream of a common distribution router. The routers who handle the hotspot stuff are all either directly connected or wirelessly connected to this common distribution problem. Other hotspot routers on our network that are not connected to this distribution router do not exhibit this problem. There are no mangle rules or anything on this distribution router.