V2.1.3.4 Bridging

I strongly don't think so simply for the fact that the switches have not been touched in over a year -- and it just so happened that the storm happened right after V2.1.3.4 was automatically installed and the fact that implmenting STP (the exact reason STP even exists) addresses this issue. It's not the managed switch doing anything. This is a classic bridge loop problem. 

The problem is that the satellite is a bridge that has two paths (wired and wireless backhaul) to the network which introduces the loop. This is a classic application for STP. STP tells the bridge to send the traffic via one path, not both. It does this by evaluating the "cost" (based on port speed) of the paths. This is what my satellite looks like without STP enabled (because it's directly connected to the router (the router has has STP enabled):

root@RBS50:/# brctl showstp br0
br0
 bridge id              8000.9c3dcfe58e21
 designated root        8000.9c3dcfe58e21
 root port                 0                    path cost                  0
 max age                  20.00                 bridge max age            20.00
 hello time                2.00                 bridge hello time          2.00
 forward delay             0.00                 bridge forward delay       0.00
 ageing time              60.00
 hello timer               0.84                 tcn timer                  0.00
 topology change timer     0.00                 gc timer                  37.93
 flags

Note the "root port" as being 0. That's because since STP is off, there is no designation on what port the traffic should go. 

Here is 'brctl showstp br0' on my satellite that where I manually enabled STP:

root@RBS50:~# brctl showstp br0
br0
 bridge id              8000.9c3dcfe5a281
 designated root        8000.9c3dcfe53026
 root port                 1                    path cost                  4
 max age                  20.00                 bridge max age            20.00
 hello time                2.00                 bridge hello time          2.00
 forward delay             2.00                 bridge forward delay       2.00
 ageing time              60.00
 hello timer               0.00                 tcn timer                  0.00
 topology change timer     0.00                 gc timer                   2.68
 flags

You'll see that the root port is 1. What is port 1? It's eth1:

eth1 (1)
 port id                8001                    state                forwarding
 designated root        8000.9c3dcfe53036       path cost                  4
 designated bridge      8000.9c3dcfe53036       message age timer         18.19
 designated port        8001                    forward delay timer        0.00
 designated cost           0                    hold timer                 0.00
 flags

eth1 is the ethernet backhaul connection to my switch. It also has a cost of 4 (the wireless backhaul connection has a cost of 100). So all bridge traffic will ONLY go to port 1 and not via wireless backhaul avoiding the loop/storm. This is STP in action as it should be.