How to turn off "Band Steering" on a modem to separate the 2.4GHz & 5GHz WiFi bands

A lot of solar inverters are not able to connect to 5GHz wifi networks, they will only connect to a 2.4GHz network. This can be a bit of a problem with some of the newer modems that use a new feature called "band steering".
With band steering turned on these modems will only output a single WiFi network that broadcasts both the 2.4GHz and 5GHz bandwidth together. The problem is that some devices don't play nicely with this feature, such as a lot of solar inverters.
The good news is that this function can be turned off, and when it's turned off the modem will again broadcast the 2.4GHz & 5GHZ bandwidth as separate networks.
This video shows how to turn this function OFF on a Telstra modem. If you have another brand of modem this video will still be helpful in pointing you in the right direction however it will be a bit different.