There is a difference in how debug logging is made in the network software for the mesh devices which prevents libraries which implements LogHandler from using TCP or UDP from within the LogHandler.
In pre generation 3 devices the firmware logs using
DEBUG("sendto(buffer=%lx, size=%d)=%d",buffer, buffer_size , rv);
but this has changed to
LOG(TRACE, "sendPacket size %d, %s#%d", buffer_size, remoteIP.toString().c_str(), port);
in the firmware for generation 3, mesh, devices…
Part of this has changed in commit 810e58a for the UDP client, but there should be similar Changes to the TCP client