Sure I see your point and have run into the scenario you pointed out regarding the WAN connection. Always best on Cisco to do "spanning-tree bpdufilter enable" for the WAN facing port. With cisco you end up with loops when switch software wigs ou...
Funny how EXOS implementation of this is really poor in my opinion. I too have fought with how to handle this as a Partner installing in many installations. I also Install Cisco. In Cisco(to prevent loops) you enable spanning-tree portfast and don...