-Squid General Settings
–- Proxy Interface(s) (LAN, OPT1, OPT2, selected)
--- Allow Users on Interface (unchecked)
-ACLs
---Allowed Subnets (added LAN, OPT1, OPT2 adresses)
Not sure why you're doing it that way. Why not just check the Allow Users on Interface box and not bother with the Allowed Subnets? They are one and the same.