I have the ports (if I remember the number correctly) 30120 and 40120 open, I have the same ports with the ip of my computer enabled in the router configuration, before I got this error but with a longer message and since I enabled port forward and others now the complete error no longer appears, just that.
Already discussed here: [citizen-server-impl] Server list query returns an error: *blank* - #5 by FrenlyDmntedNABR
Its a general problem to everyone at the moment.