Hi all,

We have recently started having issues with our VPN configuration. In summary, we have one VPN server that dials out (IPSec) to our sites (60+) who dial in, but the VPN connections (when enabled) are causing the network to throttle and Up until recently this has been working great but now we have regular issues. We had a 2960 dialling out to 2830s/2860s/2960s throughout our estate and this had been sluggish, so have since upgraded to a 3910 but are having the same issues. Firmware version doesn't seem to matter either.

The issues we're having is that the network seems to be maxing it's bandwidth when the IPSec VPN service is enabled and renders everything useless - even VOIP calls. We have a 500/500 line coming into our office so shouldn't be experiencing this when a VPN connection is active.

When the service is disabled everything works fine. Sometimes it can be enabled for days at a time without issue and then will just lock up because of a VPN connection. We have enabled the active VPN profiles in increments of 5-10 and like above, will work fine for days, and then will suddenly throttle the network, similar to a DDoS attack, and then we either need to restart the router or disable the IPSec service and then it works fine again.

Any help would be massively appreciated in troubleshooting this. Thank you.

Matt