Linux Router Problem

In your second topology, you appear to have a split subnet. 192.168.8.0/24 spans multiple switches which you state are layer 3. In your output from switch2, you have a static route for this /24 pointing at a single interface:

S      192.168.8.0/24 [1/0] via 10.58.3.254,   vlan 3

This means that traffic hitting switch2 destined for either 192.168.8.254 or 192.168.8.11 will be forwarded to the same next hop. At least one of those destinations

In order for this to work as you intend, you have a couple of options:

1. Configure switch[123] as layer 2 switches, such that the 192.168.8.0/24 is again a single broadcast domain.
2. Configure separate networks on each of the links: {device1 -> switch1, switch1 -> switch2, etc}