all my clients and this server exit to internet through one and only one astaro and one netadress 80.74.100.10

but when u type 80.74.100.12 you will enter to this server ...192.168.4.5
and all this working...
but when i try to type this adress 80.74.100.12 from one of my clients i cant enter to this server...
this adress 80.74.100.12 work only from outside network computers...

maybe i explane somethig wrong so be free to ask...
10x...