Why i cannot conect to NAT'ed host?

What you're trying to do does not make much sense. Usually you cannot nat a request coming from public address 211.123.123.123 back to the same address as if it was coming from an external host (to understand why, you should read some documentation on natting and routing protocols).

Some enterprise-class router supports the so-called "hairpin NAT" to accomplish such kind of scenarios, but this is not something that you're going to see very often in the wild.

If you want your natted services to be available on the same hostname both from the inside and outside of your lan, the smartest solution is probably to implement your own internal DNS server.

If you want to just test your NAT configuration without going out of your office you might want to make a try connecting through some public proxy (I often use Tor for this purposes). In this case, mind the security: do not provide passwords or other private data over unencrypted channels.

Some SOHO NAT routers will handle WAN loop-back, namely at least some of the Linksys & Netgear stuff.