Network congestion may occur between your modem and the exchange, or the exchange and the other networks that make up the internet.
When the network your service is using has congestion, your internet speeds are slowed down by many connections trying to use the network at the same time.
Modern networks are built to handle a high number of connections, but a drop in speed can still occur during peak hours of internet usage when almost every service on the network is being used. This typically happens in the evening - think of network congestion like the slow traffic on the freeway after 5PM when most people leave work.
Network congestion should only be temporary as it depends on the current usage of the entire network. If you find your internet is slow all the time, you may have speed issues.
Sometimes the congestion or "slow point" may not be within the Australian network. If you have speed issues only when viewing websites or playing online games which have servers based in another country, the problem may be occurring at one of the points on the way to/from the international destination. Servers can also undergo maintenance or suffer outages, which you can check on websites like Is It Down Right Now?
Running some ping tests to Australian web domains (e.g. australia.gov.au) and comparing the results with ping tests to foreign-based websites can help you identify if this is the case. You should always expect some difference in the results (international web traffic has further to go, after all) but if the differences are severe, running a trace route may better indicate where the problem is occurring.
Local congestion may occur between your devices (e.g. computers, smartphones or tablets) and your modem.
When you have local congestion, your internet speeds are slowed down by many devices trying to use your internet at the same time. The slower speed is happening because your modem is having trouble getting all of the data from each device to go through your internet connection. This is known as data flow.
Think of your data flow like a pie – the more devices that are connected to your modem at the same time, the smaller each slice has to be to make sure each device gets some.
Realistically, if one device is doing something that demands a lot of data flow, like a large download or online gaming, it may take up more data flow than other devices. This also depends on the ability of the device. To keep it simple, just remember that a computer, laptop or gaming console has a higher capability for data flow than a smart phone or tablet.
On a typical broadband cnnection, we recommend that only 5 or less devices should be connected to your modem at one time. If you have more than this, you should be fine if some of those devices aren’t actively using the internet, or if they don’t need much data flow (e.g. normal browsing, or checking emails).
If you’re concerned that some devices may be connected to your wireless when they shouldn’t be (i.e. a neighbour’s computer) you should change your wireless password.