I am new to networking and trying to setup my small office. 

Setup

I have two Internet connections

.

Wan1: Airtel (PPoE)

Wan2: BSNL (DynamicIP), it is airfiber connection and comes with its own router. 

Lan ports: 3,4& 5 Lan ports are connected to different networks

Lan Port 3: Configured VLan 20 for Office (Untagged)

Lan Port 4: Configured VLan 21 for Guest (Untagged)
Lan Port 5: Configured VLan 22 for Cameras (Untagged)

Load balancing is not enabled as BSNL connection is not stable (Airfiber). it is only used as backup or failover

I have 2 home routers and a POE switch as well. (TP-Link Archer and D-Link)

Lan port 3 -VLan 20 is connected to TP-Link Archer router for Office use. 

Lan Port 4 - VLan 21 is connected to D-Link router for Guest

Lan Port5 - Vlan 22 is connected to POE switch to NVR (unmanaged)

Till here everything works fine and no issue with the network.

I want Vlan 20 (lan port3) to connect to Wan1 (Airtel) and use BSNL (Wan2) in case Airtel goes down.

I want Vlan 21 (lan port4) to connect to Wan2 (BSNL) only. even if the Wan2 connection is down, it should not use failover.

I want Vlan 22 (lan port5) to use either, as failover is in place.

Please advise.