@Hcliffe 

Not quite sure I understand your question.  Can the 5GHz be set to run at both speeds?  Do you mean can your main network broadcast both bands?  Traditionally Guest networks are isolated from the main network so that is why you cannot see the printer while you are on the 2.4GHz network.  The simplest fix would be to set the Main network to broadcast on both 2.4 and 5GHz.  and migrate your 2.4GHz clients to this network. 

You may also want to consider upgrading to a model that supports the IoT network feature.  This would allow you to have a network isolated to the 2.4GHz band like you are doing now, except it can still see the main network. 

  @Hcliffe 

Sorry for the confusion, and thanks for your reply.  This is what I mean: Do you mean can your main network broadcast both bands? 

So if the main network can broadcast on both bands, can you provide instructions on how to do that please?  

  @Hcliffe 

 How to configure the main network to broadcast on both bands:

- open the Deco app

- click on "more" (bottom right)

- click on "wi-fi settings"

- click on the first line, showing the band(s) in use

- click on "advanced"

- click on "band"

- select "2.4 and 5"

- go back twice

- click "save"

  @Hcliffe 

This worked great, thanks much for your help.