Hi, I have the same problem. I already created the certificate, also the printer have the "epos printing" enabled, and same problem. Any another way to solve it ?

Hello Robert,

You can set up a self-signed certificate by following this link. 

https://www.odoo.com/documentation/16.0/applications/sales/point_of_sale/overview/epos_ssc.html

If this doesn't Fix the issue you can check if the epos printing is enabled in the printer. To do that you can type the IP address of the printer on any browser , a pop up asking username and password appears and you can type the password and username provided by the printer. We will be redirected to the configuration page on there we can go to settings and tick on the enable Epos printing check box. I hope this might fix your issue.

Regards