the firewall of our WD My Cloud EX4100 may block access to the WD My Cloud EX4100 after a few seconds if you want to open the network shares with Windows Explorer and the IP address via an L2TP connection.
For example, a PING to the WD My Cloud EX4100 is only successful for 1 to 2 minutes with an L2TP connection, then the connection is cut. With LAN-to-LAN, on the other hand, the PING is continuous, which is why the subnet for the L2TP connection is likely to be cut after some time.
The dashboard can only be reached with a browser with http and https for a while if there is an L2TP connection.
How can you fix this / configure the firewall? Unfortunately I have not yet found any suitable firewall settings in the dashboard of the WD My Cloud EX4100.