apple extreme bandwidth

2.4 GHz on the AirPort is 20 MHz, no more and no less. Its the default setting on most other routers as well.

Unfortunately, the 2.4 GHz band is susceptible to interference from other nearby networks around you. That's why 5 GHz was developed.

Use 5 GHz if you can. Much faster speeds with a lot less interference. The downside is that 5 GHz signals are not as strong as 2.4 GHz signals so 5 GHz only works well when you are in the same room or close proximity to the AirPort router.

The 2.4 GHz setting on the AirPorts is advertised at about 130 Mbps. In practice, the actual throughput is about half that figure. If you have several active devices on the network at the same time, the number will be even lower.