Hi there I have the same problem my phone motorola v360 and my proxy:184.108.40.206 and im on mtn
We are aware of the disconnection problems. This is being caused by a timeout problem on MTN's side. MTN's servers time's out the connection after a certain time period of no activity on all Motorola V360 and L7 phone's. Unfortunately there is nothing we can do to fix the problem. You can give MTN's customer care a call regarding this problem.
For a temporary solution you can use a HTTP connection, please note that a HTTP connection is a bit slower than normal.
When you run Mxit and your phone gives you the "Use data network" screen select "No, ask later", your phone should give you the same question again, select "No, ask later" again, your phone will ask this question a third time, this time select "Yes, ask once". You will need to do this each time you run Mxit.