Liveupdate Administration server not accessible by IP address

Hi.

I have an LUA server running v2.3.1.  It is accessible without any problems via this URL:

http://Hostname_of_LUA_computer:7070/lua

But it is not accessible via this URL

http://IP_address_of_LUA_computer:7070/lua

I get the same result even if I try the access on the server itself.  Any suggestions, log or config files to check please?