@J-C.G. Yes, your solution can work. But you may need to note it's double NAT since there are two "routers" in your network actually. It won't affect Internet access, but some applications may face...

@ralink R480T+ NAT Throughput is only 95Mbps. You won't get more speed from this router. You could buy ER605, it has much better chipset and performance.

@J-C.G. Yes, and yes. Here is an example https://www.tp-link.com/us/support/faq/3061/

@FakeApple It seems that you are doing the settings via Omada Controller. However TL-SG1024DE is not an Omada switch and can not apply the settings from the controller. You can try Gateway ACL....

@Upakovkashop CPE610/CPE710

@jayb1 Are you still be able to Ping this switch IP? Try login the switch via IP address