I thought LTE is a kind of wifi, like WiMax...
Both Mac and 4S are connected to the same LTE wifi. This LTE can cater 10 different divises to connect to the internet. Mac and 4S are using two slots, so to say.

And there's no firewall as far as I know. I never set it.

No, the only changes made since the last successful synch are:
1) Changed my phone from iPhone 3GS to 4S
2) Started using LTE mobile wifi connection for both Mac and 4S, instead of ground LAN cable for Mac + Air mac sharing for 3GS.

I didn't change any fire wall setting or anything....

Thanks Zeliboba, yeah I think it's pretty similar. So does that mean there's nothing I can do about it now?

Thanks, of course I tried that, but still the "device" field is blank and the iComputa on my mac doesn't recognize 4S.

I have been using iComputa on my mac and my old iPhone (3GS...) since last November and never had a problem synching the two. I just changed my iPhone to 4S, copied all my phone settings through iTunes, and I haven't been able to synch iComputa mobile on my new iPhone to the iComputa on my mac. This ...