Combine five internet providers into one for your office.
Combine five internet providers into one for your office.
The issue with this approach is that the router will handle all traffic for the NAS and internet connections. If the connection to the NAS is large, performance can drop on the internet when the NAS is busy. It doesn’t make sense to route traffic through routers for NAS access when a simpler method exists. Based on my current setup (each floor using its own router with DHCP), the best option is to install five network cards on the NAS so it can connect to all five subnets. If you must use only one network adapter on the NAS (or if there are multiple NAS units), connect the floor switches to the NAS port and set up VLAN tagging so only traffic from other floors reaches it. This keeps the network intact and ensures each floor stays on its own subnet without going through routers. The final step is to set the NAS to use the preferred ISP as its default, giving it access to all five connections.
I believe a multi-CDN configuration fits your requirements best. It helps lower latency and adds redundancy. Various options exist to suit different needs. You can choose load balancing and failover features.