For the Rollo wireless printer. Always ensure that you are connected to the same WiFi name and the same band 2.4Ghz or 5Ghz.
This is not an official Rollo support site, for the official support site, please visit: support.rolloprinter.com
If your merchant (i.e Mercari) or carrier (USPS, FedEx, or UPS) has no option to generate the labels in 4 x 6-inch thermal printing, you can go ahead and crop your labels using adobe reader.
Download the free version of the adobe reader here: https://get.adobe.com/reader/
Once, you installed Adobe reader, locate your shipping label and open it using adobe reader
(For Windows, Right-click on the file and select open with Adobe reader)
(For Mac, press the Ctrl (or Control) key + Click on the file and select open using Adobe reader)