I'm not sure if I understood your point, sir. My setup is like this, Cisco SG300 then to connect TPLink SG3210. I used Port 10 of Cisco SG300 now as trunk (uplink) then Set Port 8 of TPlink SG3210 as...

Yes and yes. The VLAN 21 can get IP from the said DHCP server. However, the subnet it gets is the subnet of the VLAN 20.

Sure, but it is quite long. I'll just have to past the link where I posted in Spicework about this issue. I've had screenshot as well:...

I have read that tutorial and tried to follow it. It works though, but for VLAN 20 only. I only have 1 DHCP server. My setup work with all my cisco SG300 switches.

I would like to ask help. I have a Cisco SG300 switch running as Layer 3, with VLAN 20, 21. Enabled dhcp relay for VLAN 20 and 21. Then on the TP Link SG3210, I set VLAN 20 and 21 then both connected...