Devices in the local home network not anpingbar why?

Have a great Connect Box from Unitymedia,

so the router so the default gateway I can ping from my laptop all other devices that are not connected to the router.

Thus does not believe the RDP connections between the devices in the network.

Why is that? Is it at the box?

Maybe you're connected to the guest network. In the guest network you can by default no other devices "see or use" not even ping. Check that, something is set in the router.

Try the firewall on the laptop.

And the network connection on the laptop should be set to "private network", not "public network".

Ping does not necessarily have to be allowed by the device…

Especially with Windows this is not always activated. Important is first that you know the correct IP of the PC to be controlled in RDP. Hostnames may not be applied to the new router.

Windows can also distinguish the networks and has now set the new network as "public". Here is the release of the RDP port 3389 mostly disabled, so here's a look, if you have in the Control Panel> Network and Internet under your network "Private Network" are.

Does the ping work on at least some other device? There's also the setting "AP isolates" on the WLAN, which blocks the communication between WLAN clients.

Thus does not believe the RDP connections between the devices in the network.

Faith does not help. Just try it out. RDP can work without the ping working. The firewall of the Connect Box may be blocking the ping or ICMP.