Port Forwarding

When applying Port Forwarding via the web site (as it's now disabled from within the gateway login itself), does it apply to all devices connected to the gateway? 

The new web interface asks to select a device first. However, when assigning the same port forwarding to a second device in the list, it tells me that the port is already assigned to the first device and to select a different port or delete the first entry. This is to prevent the mobile company's WiFi Calling from repeatedly disconnecting. I would like to be able to assign the same ports a least to more than one device, otherwise make it apply to everything connected to the gateway.

Thank you in advance.