Help please - WAN latency goes nuts as soon as anything uploads.

Hi All,

If anyone can give me some ideas/advice on the below, I would be very appreciative.

I have taken over looking after a customer with about 30 PCs on their LAN. They connect via a Sophos UTM (SG210) to a virgin media service (50/5MBit).

I have found that the latency when pinging 8.8.8.8 from the LAN is normal (say 25ms) when there is no outbound traffic. As soon as any data starts leaving the LAN, the latency will jump up to well over 250ms.

I tested the same from my LAN (we use Mikrotik firewalls), and found that even when I saturate my WAN connection outbound (with a speedtest), my pingtimes are still reasonable.

I have no idea why this would be…today, in the QOS settings, I defined the outbound maximum bandwidth as 4.3Mbit to see if that makes a difference, and it doesn’t.

Thanks in advance for any assistance.