About interface bandwidth limits
You can limit the available bandwidth for incoming and outgoing traffic, for each interface on your Smoothwall that you want to shape. We recommend that you configure slightly less than the expected maximum throughput of that interface to be certain of avoiding packet queues. Typically, this would be 95% of the expected maximum. The user assistance procedure assumes you've configured your Smoothwall to either process external traffic, or as a bridge.
Typically, you don't need to remove interface limits configured for shaping. Removing a shaped interface doesn't remove associated classes from the bandwidth configuration as they're available to all shaped interfaces.
All classes are assigned to the new interface by default, with the Maximum bandwidth in, and Maximum bandwidth out set to Use interface limits and the share Type set to Dynamic. However, you can amend this.