I faced Juniper firewall connection issue with Juniper Network Connect Client from my machine to the remote firewall about one week. Even I removed my machine from domain, assigned a public IP, disabled local firewall and antivirus but no success!
We troubleshoot the issue by following steps:
1. We logged onto the machine with domain administrator even after removing machine from domain instead of local client admin and enforced the group policy to domain policy by using the command gpupdate /force. Because there was a policy in active directory server which was preventing to install juniper virtual adapter on my client machine as part of connection process.
2. We uninstalled VMware virtual adapter and finally VMware software itself because we thought it might be conflicting with connection process.
3. Finally we come to know that DHCP client service was not running at my machine and most probably it was causing the conflict in connecting to the firewall.
It wasted about a week in troubleshooting the juniper client connectivity!