I've updated the diagram to include port states, root switch, and hostname. My concern is with switches S1 and S3. Their connection to each other is the RP. When I do a show spanning-tree vlan 4 on S1 and S3 those particular ports show Root FWD. I'm certain I was looking at the correct ports for each because I enabled CDP on all the switches. Is this okay or did STP converge wrong?
something is wrong; RP is upstream port or pointing to the Root;
and DP are downstream ports or away from Root;
you cannot have DP-DP or RP-RP on same link and on the same Vlan.
each non-root switche should have one Root port, all other ports are DP or Blocking.
Cisco STP is per Vlan STP; one instatnce of STP runs per one Vlan.