Might be conflicts due to several routers using the same subnet… could cause some interesting ARP issues for the switches, and also DHCP conflicts if something is wrongly cabled / configured.
I would try disconnecting everything from after the first switch, connect a computer there to see if it works ok, then reconnect and test behind each step to see where it breaks instead of checking in the end where the problem could be agitated from a issue earlier in the network…
also, if the router has a firewall/nat you will not be able to reach anything behind it, even if there are different subnets being used… to be able to reach devices behind a router, the network would need to be routed and not nat’ed as nat combines all network traffic into the IP of the router before sending the traffic away, so clients on the other side has no way of knowing who or where the traffic came from after the nat’ed router.
I suggest you read up about this if you are not familiar with difference between NAT and routed traffic.
anyway, this is just my theory, hope you find your problem and get it sorted :)