Captive Portal and Download Errors

[MagnaPilot]

Hello,

I've been dealing with this issue for some time now, generally I've just disabled our Captive Portal to get around it.  I had hoped it was something that would be fixed, but it could be a configuration issue that I cannot locate.

I'm running a 17.7 box, using IDS, Upnp, basic firewall and dns, nothing very special.  My issue is when captive portal is enabled, users cannot download files much larger than 20-30 MB before the connection is suddenly dropped.  I have found no rhyme or reason, but it does not do this when the Captive Portal is disabled. 

The portal is pretty standard, web login or MAC authenticated, no proxy of any type.  It doesn't matter what type of device, or if it's an http or https connection. 

I'm at my wits end with it, as I've been dealing with it for over a year.  Does anyone have any ideas what could be causing this?

[MasterXBKC]

sounds almost like captive portal is timing out the state table entries which are involved in the download which breaks the connection, you would have to confirm it tho.

[MagnaPilot]

Thank you for the response, I'll look into that and see if I can find anything of interest.

[MagnaPilot]

Just a brief overview at what I'm dealing with, perhaps those more versed can more easily spot the issue.  Attached is a Wireshark screen capture of a download from my PC, with the Captive Portal enabled.  From what I see, the connection starts fine, and gets worse, progressively requesting more and more re-transmissions until it finally gives up.  What gets me, is that it only does this with the Portal enabled.  I've checked the load of the server itself both enable and disabled, and there doesn't seem to be any issue, nor with memory or the state tables. 

Attached is the screenshot.