Our router began crashing 6 weeks ago. We put it down to our DSL provider and then to power outages that seemed to coincide. But the crashes increased in regularity and then last Friday our router crashed maybe 10 times in the one day. And we still don't know why. When the router crashes it becomes unpingable (internally or externally) yet the router lights flicker on just like they should. Since black Friday we have

  • updated router firmware to latest version
  • swapped the router for an identical model
  • rolled back all recent edits to router configuration to a happier time
  • eliminated the DSL lines as the issue
  • ensured that our AV Eset Nod32 is up to date on all clients
  • removed wireless access for all

The crashes have stabilized somewhat in that they now happen every 48 hours or so. We are syslogging router output but have found nothing, so far.

The router is a Zyxel P600 series, model: P-661HW-D1. We have a vpn with port forwarding and some firewall rules. Clients are xp, vista & win 7. Why are these crashes happening and how can we get to the bottom of it?

  • What's the router model? (P600 describes a series of about 16 routers.) – David Schwartz Mar 16 '12 at 1:11
  • Hi David, router model is P661HW-D1. Detail added to the q above. Rgds – Rory Mar 16 '12 at 9:02
  • The P661HW-D1 crashes if you exceed about 900 NAT entries. Clustering downloaders (like Bittorrent) can do this. – David Schwartz Mar 16 '12 at 17:26
  • The max number of NAT/Firewall sessions per user was set to 512. So I have just lowered that to 150 (kind of randomly chosen). Thanks. – Rory Mar 16 '12 at 20:32

For business use? Replace it with something that doesn't suck balls. I can recommend the Juniper SRX220, or Cisco 1900 series with an ADSL HWIC.

Internet access is the life-blood of any business these days. Why save money on hardware when cheaping out can cause outages which are distruptive to both business activities and productivity.

  • Yes, for business use. We are investing in new hardware which is one of the reasons we were so blazé about the crashes to begin with. – Rory Mar 15 '12 at 21:52
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    I'm very dubious of home-grade use for business. It's designed for a far lower usage cycle/ duty-cycle. I bet it's overheating and resetting itself. – Tom O'Connor Mar 15 '12 at 22:12
  • I should have mentioned - we have a fan cooling it down just in case. – Rory Mar 15 '12 at 22:17
  • "Replace it with something that doesn't suck balls". Tell us how you really feel, Tom. :) – joeqwerty Mar 15 '12 at 22:32
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    BTW, that's now my standard answer for all customer questions. – joeqwerty Mar 15 '12 at 22:33

In our offices we use Zyxel P660R-D set up in full bridge model to something more substantial for PPPoE and firewalling.

Your Zyxel P600 supports full bridge, so you can pair it with a more substantial firewall, like a Zyxel USG 100 or D-Link DFL-800 (great piece of kit, it is a re-branded Clavister, but now EOL - so Ebay only).

The issue you are having is very likely to be too many sessions open/connection tracking. Little SOHO firewalls like that really struggle if you've got multiple FTP/SSH/HTTP sessions active and they fall down with as little as 300 active sessions.

Ps. The Zyxel P660R-D is rated as being one of the fastest ADSL modems too (provider DSLAM/MSLAM chipset dependant). See http://www.thinkbroadband.com/news/4144-how-fast-is-your-broadband-router.html

  • I use a TPLink something as a PPPoA-PPPoE modem, then a Cisco 2621XM for home use. It's a good combo. – Tom O'Connor Mar 15 '12 at 23:00
  • Thanks Sonassi - that's exactly what we did. We got a Fortinet device for firewalling and put the Zyxel in bridge mode. – Rory Apr 17 '12 at 21:52

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