On a sunny day (Fri, 28 Sep 2018 07:53:18 GMT) it happened Alister ware
 wrote in :

>I am trying to configure my printer using the Hplip gui but discovery
>always fails
>On my other linux boxes manual specifying the ip address of the printer
>will suffice to overcome this but it does not seem to  work on my Pi3B+

Is your printer on the same IP address range as the pi?
For example if the pi is at
192.168..
and the printer at 10.10..
it will not work.

typing
 sudo ifconfig
will tell you the pi's IP address.

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