b2789 clients will not be able to connect to servers running older versions of R1Q2 unless you set cl_protocol 34. This is not a bug, it's a protocol change in the R1Q2 enhanced "protocol 35". I've broken compatibility a number of times in the past when I had a much smaller user base, so I'm posting this so that people don't start reporting it as a bug
. To connect to an older server, set cl_protocol 34 to use the default Q2 protocol until the server upgrades. Likewise, old clients won't be able to connect to new servers.