Are you using Cisco devices?
Here are some factors to condisder in troubleshooting:
If your using cisco.
1. try to check the configuration of the subinterfaces on your router, you said that you’ve added additional router with different vlan ID, maybe you haven’t included that into your subinterfaces.
2. On your added router, try to configure a default route onto outgoing network, maybe the packets from the inside network can’t go outside because of routing. As you can see, If your using a switch in vlans, they are in the same network, if not, they are in differnt vlans but ip address is not a factor for a switch. In a router, 1 port/interface equals 1 network.
For me, it is not advisable to add a router down to your vlan network but its ok if you know how to use your devices.