Yes, I have seen that message - along with many other TCP/IP-related error messages - from the 540.
Our testing has shown the TCP/IP stack in the 540 has a lot of problems. Too many to list here.
Last year I sent some example software I wrote, which crashes the 540's TCP/IP stack on demand, as well as a bunch of tapes showing the resulting error messages, to the Canadian TAG Heuer distributor, who then forwarded the material to Switzerland.
To date TAG Heuer has not addressed the issues.
I might add that the serial port on the 540 has performed fine in our tests. Other than the botched attempt at TCP/IP implementation, it is otherwise a pretty solid little machine if you can get past TAG Heuer's bizarre choice of connector hardware.