I was referring to the routers loopback capability, not that of an individual machine. Thus the ability of the router, to receive a packet from a local networked machine which is addressed to the routers internet IP. Then point it in the direction as per port fowarding rules to another networked machine (192.168.0.1(81.1.2.3)->192.168.0.0(81.1.2.3)->127.0.0.1(192.168.0.2)). The involves two technologies which Belkin routers don't support - HalfNAT and loopback.
Replacing IPs in the server config doesn't work. There exists two configurations that work. Local LAN access only, Internet&Self access only.
This is opposed to the situation in 1.4, where it was possible to configure multiple configurations through the DBServer.
Its all about which IP the server instructs the client to use, and what the client does with such instruction. There are number of things that are possible here. The easiest being a client which favours the mir.ini IP over that submitted by the server. The other is running a proxy which intercepts the login sequence, and changes the instruction on the fly - the method which I've used with success.
So it therefore is a question of identifying what router the OP has, as to determine if its a lack of router capability, or lack of correct server configuration.
/Leo