@OZ-ZERO 

What are you going to use it for then? A router in the network is enough, if you need a switch then you buy an Omada managed switch, they cost almost nothing. SG2008P or an ES205GP, if you are going to use the router you have now as a switch it will just be a mess, so I wouldn't recommend it

if you need more info about the products then look here

https://www.omadanetworks.com/en/

  @MR.S 

I think you misunderstood. I have already spent money on the ER7212PC; and it's used to power 2x POE wireless access points as part of the network.

Instead of spending money on another smart switch, I wanted to know if this can actually connect to a standard Omada VPN router.

My network is seperated by 3x different locations.

At present everything works completely well - other than the fact I am missing DoH / DoT.

Hence:

Internet modem --WAN--> ER605

ER605 LAN port 1-> TL-SG3428MP v4.0 -> EAP and wired ethernet

ER605 LAN port 2 -> ER7212PC -> 2x POE EAP610

ER605 LAN port 3 -> TL-SG116P -> EAP and wired ethernet

Does the above setup make sense? Furthermore, can the ER7212PC in built Omada controller bypass the need to also purchase the OC200?

  @OZ-ZERO 

I don't know if there is a DNS proxy in stand alone but in theory you can use an ER605 in front of the router you have today,