Since we have connected the POS application, we encounter problems of printing our invoices. It is an "on and off" problem. When we cannot print, this message appears : 

"Please check if the printer is still connected, if the configured IP adress is correct and if your printer supports the ePOS protocol. Some browsers d'on't allow HTTP calls from websites to devices in the network (for security reasons). If this is the case, you will need to follow Odoo's documentation for "self-signed certificate for ePOS printers and "secure connection (HTTPS) to solve the issue."

Our certificate is installed.

The IP adress is correct

Anybody here face the same issue and managed to resolve the problem ?