Hello, 

The last few weeks I have seen high CPU usage on our Vigor 3910, spiking to about 88% and mostly sitting around 40% during the work day.

It's causing concern as users are reporting issues with their phones and connectivity to the systems and our RDS particularly for remote workers seemingly when the CPU spikes.

I am running 4.4.5.1, but the issue was present on the previous FW version too.

We have a 1Gbps/1Gbps connection, running a few port redirection rules, QoS with VoIP prioritization enabled and there are two site-to-site VPNs.

Has anyone got any suggestions as far as the high CPU usage is concerned and any ideas where I should be looking first?

Thanks

I've no real expertise here and may be things you've considered:

Are you logging to syslog somewhere so that you can go through that and see if there's any commonality? My Draytek environment seems to get completely stuffed by zScaler on my wife's laptop - 700 DNS queries in a second... zScaler say that's how the product works.

I'm not sure that the phones performance is something I'd focus on; is there logging on the access points?

You've not mentioned your topology; I assume you've got more than just a 3910. Are there performance issues when on the internal network as well as connecting from outside the network?

I think I saw something recently about performance issues with a specific VPN method (can't remember the method or source!). What method are you using?

Have you recently upgraded to 4.4.5.1? You said "the last few weeks" but then said it happened on the previous FW version (was that 4.4.5?).

I'm not actually sure that the CPU is the issue of performance; I mean, if it's normally at 40% and spikes to 88%, it's not CPU-bound. Could it be connection bound? Or memory? What is System Maintenance / Max Connection? I think some people have increased that (tho to me, 300k *seems* a lot but I guess if there's lots of people running zScaler client...)