I have a client who has isa server connected to isdn router! For a strange reason every 15mins or so , the line goes active, I have read various msg boards, I have checked caching, not enabled, changed dhcp client service, check LAT table config, however if you check the IP event log here is a DNS port 53 blocked, however it would appear to life the IDSN line high. Anyone got any sensible thougts or suggests, DSL aint an option.