@Rduhb You need to set up L3 interface. Like the following picutre, edit IPv4 address then choose DHCP.

@ken22 I can only think out the solution that upgrade the latest firmware. The firmware download link is as follows. https://static.tp-link.com/2019/201903/20190322/TL-R600VPN(UN)_v4_20190227.zip

The configuration is alright. When the problem happens, you can try to disable web filtering, it's for confirming the problem is caused by the feature. Also can try to upgrade the latest firmware.

If your ISP is assigning the IP address thorugh DHCP, then the switch may get the IP address from ISP. If through PPPoE other other way, DHCP will not get the IP address. Generally VLAN 1 is used as...

@y_u_1000 Do you mean that you need to disable NAT function? Unfortunately ER6120 cannot do that unless you use V1.0. Because the NAT exist, you cannot ping the devices from WAN side.

@foobar Do you need to separate Plex traffic and IPTV traffic? TL-SG105E 1 port 3 VLAN 10 untagged PVID 10 port 4 VLAN 20 untagged PVID 20 port 5 VLAN 10 & 20 tagged PVID 10 OR 20 TL-SG105E 2 port 3...