As long as melee aren't playing as a team and protecting their archers, I can kill them using a shield. Unless there are more than 1 ranged working together, then I find it impossible to solo them. Why can't I solo multiple players at once?
First, I can not kill "them", I can kill
one.
Second, I probably spend a good 10 seconds average chasing and fighting and probably get myself killed shortly after killing one, or before, as even if melee don't actively defend ranged they are often in the way and can be a bitch to disengage if they really want me dead.
Third, "ranged working together" just means "ranged with line of sight between each other". It's not active teamwork, it doesn't require any effort.
Fourth, I am more than able to solo 3 or even 4 melee players on a regular basis, with the same build. That build is one of the least terrible melee "counters" to ranged yet it is definitely much better at fighting melee than at fighting ranged.
Fifth, do you never see archers or xbowers soloing multiple melee players ? Because I do. I don't see what would be the problem with shielders soloing multiple ranged.