Network switch selection for VLAN design

CKopp wrote:

can I get away with replacing the 8 port Port switch at B and put a new 4 port switch between the IOT devices and my main 24 port switch. 

FWIW, you haven't said how the streaming devices are connected.  Are they also connected only to switch A and B?

Another aspect is how much isolation you want for the IoT devices.  You won't be able to isolate them from the wifi network with this arrangement, since the RS routers don't have the VLAN features you need.  I am assuming you want that isolation.

You could connect a wired router (or L2/L3 switch with routing functions) to the modem, and then use the RS router as an AP.  As far as Netgear kit goes, the GS728 series switches have routing functions built in, so you could potentially connect one of those to the modem.  Ideally this would replace switch A, though that depends on whether wiring allows that. Check the manual to make sure it has the routing functions you want.  

• https://www.downloads.netgear.com/files/GDC/GS728TPPv3/GS728TPv3_GS728TPPv3_GS752TPv3_GS752TPPv3_UM_EN.pdf

Of course, one of Netgear's fully managed switches would also work as an edge router.

Is the modem actually a gateway (perhaps in bridge mode)?  If it is, you could use the gateway as the edge router (turning off the wifi), and continue to use the RS router in router mode.  Then use switches connected to the gateway for the wired IoT devices.   These could be unmanaged switches, since the NAT in the RS router would prevent the IoT devices from reaching the RS router network.  The RS-connected devices could still reach the IoT devices.  The downside here is that you'd have a double-NAT configuration.  This is managable, though a bit more complicated if you do port forwarding.

The third option is to get a new small wired router with full VLAN support, and use the RS router as an AP.  Unfortunately, Netgear doesn't sell one, so you'd need to use another vendor.  As far as switches go, if you have only IoT devices connected to switch B, you'd be able to use connect it to the wired router, and set up the router LAN port as an untagged VLAN.  You could also get a small smart switch to connect the IoT devices currently on switch A to the wired router (also connecting that to existing switch A).  The GS305E or GS308E switch would work for that.