im not directly effected with this change
but here is my thoughts

1.You have directly shared an IP address with the province you are attacking or aiding
the aid thingy surely wont work
since we can always send to some1 else in the kd, then s/he resend the aid
if its blocked with the interact, then resend to another prov ( the 4th prov not interacting with 1st prov aka sender)
2.You are attacking a province who has recently been attacked by other provinces that have shared IPs with you.
recently?
how long does it take for the effect to wore off?