WebRtcServer depends on ICE to work and obviously there is no ICE in PipeTransports, so not possible. However I don’t understand the problem. You just need a single PipeTransport pair to interconnect 2 mediasoup servers. If you create a mesh of servers then you need different ports for them.
As you say, I am currently using mesh of servers. Because of that, I have to manage (mapping) the extra port numbers when creating the pipeTransport, so I’m thinking I can take advantage of webRTCSever again. Thank you with useful information.