Sonicwall tz190 drops WAN traffic after 10 - 20 mins
Posted on 2009-02-24
We run Sonicwalls for all our external connections. On Friday our subsiduary office noticed their internet connection was down and contacted their cable company who said the modem was reporting "wierd issues" so they sent someone down to replce the modem. 15 mins after the tech left the connection went down again.
The IT guy at the office discovered that rebooting the sonicwall brought the connection back up but it would fall over 15ish minutes later.
We've been on the phone with sonicwall and tried all of their ideas so far, plugging only one client computer into the firewall, upgrading the firmware, checking the number of connections etc.
The strange thing is, if you change the WAN connection from a static address to a DHCP address (or the other way around) the connection comes back up as if the process of changing the interface (down up) clears something somewhere.
I discovered that if you clear the ARP cache the connection comes back up as well.
Now I've found that if I set the "ARP Cache entry timeout " down to 1 minute from the default of 10 internet connectivity still drops but only for a few pings then comes back up.
By connection dropping I mean you just can't ping anything on the WAN side although as far as i see the sonicwall reports nothing wrong in any logs, it just silently starts dropping WAN traffic.
I'm also not sure whether this happened first or if the change of cable modem is causing some incompatability somewhere.
Anyone got any ideas before i speak to Sonicwalls call center again :-(