Re: VPN Drops every 9 minutes

"Ian" <ian_agerskov@xxxxxxxxxxx> hath wroth:

I have a client that lives in a rural area and connects to a wireless ISP,
when she connects to the office via pptp vpn she gets disconnected every 9
minutes, give or take 30 seconds.

ISP uses Tranzeo radios. In her house she uses a wireless laptop connected
to a wrt54gl running dd-wrt 23 sp2.

Her office is running server 2003 for remote access behind a sonicwall
tz170.

Is the PPTP server terminated in the Sonicwall or in the Windoze 2003
server?

To see if the problem was her laptop I tried using the dd-wrt pptp client to
connect and left it run overnight. Server logs show drops approx every 9
minutes. I then tried using the dd-wrt client to connect to a different
server at my office. Same thing the vpn drops every 9 minutes.

Something is kicking her off, the only thing I can think of is a weather
radar station located a few miles away. Could this be the culprit? Anyone
have any ideas as to what else could be causing this?

Not enough info to make a conclusive guess. It could be literally any
source of RF. See list of probable culprits at:
<http://wireless.wikia.com/wiki/Wi-Fi#Interference>
Offhand, I don't see anything on the list with a 9 minute cycle time.

I use the PPTP client and server in DD-WRT v23 SP2 and SP3 without any
dropouts, so that's not it. There is the "scheduled reboot" feature,
which may have accidentally been setup. See:
<http://www.informatione.gmxhome.de/DDWRT/Standard/V23final/Alive.html>
That's probably not the problem, but might be worth checking.

If the VPN is terminated in the Windoze 2003 server, look in the
"Event Viewer" for clues as to which end initiated the disconnects and
what was happening when it disconnected.

Also monitor connectivity during the critical 9 minute period. A
simple ping running every 5 seconds should be sufficient. If the
pings disappear at the same time as the VPN goes down, you've lost the
RF link, probably due to RF intererence. If the pings continue
normally when the VPN goes down, then it's something in either the
PPTP client, server, or Sonicwall router.

Don't ignore the in between boxes. I had an allegedly working router
drive me nuts by silently rebooting every 2 hours. No evidence of a
reboot in syslog. I eventually noticed that the uptime was unusually
low, which pointed to the reboots.

If it points to an RF problem, you'll probably need to buy or borrow
some form of RF spectrum analyzer. Check with the local hams or try
Wi-Spy at:
<http://www.metageek.net>
Ouch. $400. I paid $100 when it first was introduced.

Well, this one is $100 for the "lite" version, but I don't know
anything about it.
<http://www.nutsaboutnets.com/performance-wifi/products/product-airsleuthlite-wifi-spectrum-analyzer.htm>

--
Jeff Liebermann jeffl@xxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
.

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