[jadmin] difficulty with s2s to jabber.org

[Charles Duffy]

I'm having trouble with s2s between isgenesis.com (our Jabber server is
chat.isgenesis.com) and jabber.org (in particular, I'm trying to join
some of the rooms at conference.jabber.org). I'm quite sure this issue
is on my side -- I can't interoperate with GTalk either -- but I'm
scratching my head as to why.

I have proper SRV records set up:

$ dig +short SRV _xmpp-server._tcp.isgenesis.com
5 0 5269 chat.isgenesis.com.

...and reverse resolution, propagated to external servers:

$ dig +short chat.isgenesis.com @132.241.66.6
168.215.170.38
$ dig +short -x 168.215.170.38  @132.241.66.6
chat.isgenesis.com

However, external jabber servers refuse my outgoing s2s connections
outright:

1629.155651 168.215.170.38 -> 208.245.212.98 TCP 54614 > xmpp-server
[SYN] Seq=0 Len=0 MSS=1460 TSV=334743079 TSER=0 WS=2
1629.195582 208.245.212.98 -> 168.215.170.38 TCP xmpp-server > 54614
[RST, ACK] Seq=0 Ack=1 Win=0 Len=0

Incoming connections on port 5269 are accepted.

What should I be looking at to understand the issue here?

Thanks!