Ideas
Ok, I'm starting to piece this together. If your NIC is gigabit, and you start a match, you are going to get kicked because JAC is going to disconnect your NIC. This is most likely a side effect of JAC changing parameters on your NIC to sniff traffic (probably by kicking it into promiscuous mode, I'll test this theory out). Another side effect is it's going to kick you down to 10 Mbps or 100 Mbps. If you get kicked to 10, you're done. If you get kicked to 100, you'll be able to play for a few matches before getting kicked again.
Luckily, I happen to have a few Juniper switches sitting around my home lab and I'm going to set up a port mirror and sniff the port traffic with a linux box running on my Nutanix CE cluster (via tcpdump). Yeah, it'll generate a massive dump file, but I guarantee the match will only run for 5 or so minutes before getting kicked.
The NIC parameter change sounds plausible, since if you quit the game immediately after getting kicked, you have a disconnected NIC, then it comes back online in a bad state. You either have to reboot to reset the NIC --OR-- wait it out. In fact, I just watched my NIC disconnect, and reset itself back to gigabit as I was writing this.
I'll set this up --soonish--.