Hi,

I have ISP -> Router -> Switch1 -> Switch2.

I have NAS in VLAN 10 (192.168.10/24) connected to Switch 1.
I have a PC in VLAN 20 (192.168.20/24) connected to Switch 2.

Router: ER7206
Switch 1: TL-SG2210P
Switch 2: TL-SG3210

All managed via OC200.

As of now have those VLAN/Subnets configured via Settings->Wired Networks -> LAN.

First:

Purpose: Interface

VLAN: 10

Gateway/Subnet: 192.168.10.1/24

DHCP: Enabled: 192.168.10.100-199
Default Gateway: Auto

Second:

Purpose: Interface

VLAN: 20

Gateway/Subnet: 192.168.20.1/24

DHCP: Enabled: 192.168.20.100-199
Default Gateway: Auto

When I disconnect Router from Switch 1 while pinging from PC to NAS I get an error. This makes sense, as the router is set as default gateway for out of subnet traffic.

Question:

How to set it up so that Switch 1 will work as a gateway for VLAN 10 and 20 so that all traffic between those goes via Switch 1 and not via Router?

My own investigation:

This below might be total gibberish on a technical level but this is my thinking. Please correct me if I said something wrong. I want to learn.

I know that I need Switch 1 to be visible to downstream clients as a gateway (now it doesn't have IP address other than management one on management vlan).

Additionally, I know that DHCP needs to advertise Switch 1 as the default gateway.

But I don't know how/where to set it.

I found "VLAN/Subnets configured via Settings->Wired Networks -> LAN -> First -> Manaul Gateway" option but don't know what it does.

I also found "Switch Settings -> Edit Port Profile -> Config -> VLAN Inteface" for both switches. There I can setup separate DHCP etc. 

I can see that I can set DHCP or Static IP for Switch (?) here. I can also set DHCP mode to None/DHCP Server/Relay. My guess is if I want Router to give out addresses then I need to set it to None or Relay. If I set it to none will will the Router give out IP to client? If yes, then what does Relay option really do? Please guide me in the right direction.