If SYS LED remains dark, it means that the switch isn't working. Did the problem happen after install the latest firmware? If so, maybe caused by this upgrading. Did you see any abnormal phenomenon...

1. All staff will works together as one network. Because you use the unmanaged switch, so all devices will be able to communicate with each other. 2. ER6120 and SG1008MP can be on 19' rack.

If you use CLI command, you can try to enter two IP addresses. Another IP address is backup-ntp-server. If you use web interface, is there any error message when you configure NTP server? Please note...

If you can found the cause, you can share here. I am also curious about how can make port dead. But if your network can work normally all the time, it's also a good thing.

@Yos You can go to TP-Link official website. For the menu on the top of their website, there is SUPPORT menu. You can check whether has email support. Sometimes their engineer will look this...

@Yos I think you need to set up two items for policy routing. 1. Make IP_GROUP_1 go to WAN1. So source IP of this item should be IP_GROUP_1, destination and service type is ALL. Choose interface as...