From what you say it sounds like the firewall (NIS) needs an update of progs that are allowed to access the internet. The LU1814 message usually points to that.
Go into NIS and find Internet Access Control, when it shows the list of progs currently with permission, highlight them all and "remove" them. Then run the Application Scan for all drives that have programmes. When the listing is finished, use "select all" which ticks each item, and then OK/close.
That will usually sort it. If this is confusing, just ask.