I have a home network and access a desktop computer from my laptop (both Win 10) using Remote Desktop. This is using an internal IP 192.168.0.XXX. Most of the time it works fine but a few times a day I cannot connect or the connection drops getting the standard Remote Desktop connection error. From the laptop if I ping the desktop IP no packets go thru. If I ping the desktop using either the external IP or DDNS host name it works fine. Note I do have port forwarding set up in my Asus RT-AC68U router to access the desktop from the outside world. I can ping the other clients on the network fine just not the desktop. Whats weird is from the desktop window on the laptop I can ping the other network devices just fine. Access directly from the desktop works all of the time too. It is not a laptop issue as my iPhone 6 can't ping the desktop either but can the other devices on the wifi network. This has me totally stumped.
What could cause this? I have tried rebooting the laptop, desktop and router but only time solves the problem. Even when I can connect via Remote Desktop ping does not go thru. Could this be a loopback problem? I do run the latest Merlin firmware in the router.