Charging ports experience a lot of traffic in plugging and unplugging. Most likely in this situation the charging port has become “worn out” in that the connection may have experienced some slight bending or rather become “warped” and now can no longer hold the cord in place properly. The best fix for this would be to replace the charging port and the connection will be as it should. However in some cases the repair cost can outweigh the cost of getting a new device. Hope this helps.