Siemens SIMATIC S7-1500 Function Manual page 299

Routing
10.3 IP forwarding
Restrictions
You cannot configure any additional IP routes other than the router ("Standard Gateway") for
an S7-1500 CPU. The network destination is either a connected IP subnet, or the network
destination can be reached via exactly one configurable router. Because the S7-1500 CPU
does not support additional IP routes, you cannot build bi-directional IP router cascades.
In the following configuration, you can configure either "Router 1" or "Router 2" in the CPU.
"Router 1" is configured as an example. In this case, you cannot configure "Router 2". IP
communication between the PC and the HMI device is not possible because the route is not
continuous in both directions.
Figure 10-9
298
Unsupported IP router cascade
Function Manual, 11/2019, A5E03735815-AH
Communication