Adding back some Left 4 Dead servers that I have, I realized that the complete list does not appear on the page and opening the game only one of the three servers that I have running appears.
These are the IPs:
192.223.27.174:27005 DSLive | Versus #2 | 1.0.3.1
192.223.27.174:27015 DSLive | Versus #3 | 1.0.3.1
192.223.27.174:27020 DSLive | Versus #4 | 1.0.3.1
Best regards.