S7 1500 FW 1.0 TCP/IP Problems

I have a S7 1500 PLC Firmware Version 1.0.1. The Ethernet port will not stay connected to Portal Version 12 SP 4 more than about 45 seconds.
The display on the front of the PLC will show "Connecting" The PC will announce the port is connected. Portal V12 will communicate. Meanwhile the PLC front panel displays "Stop" all communications are Ok during this. After about 45 seconds the PLC front panel displays "fault" At this time all communications stop and the PC announces the cable has been unplugged. WHAT am I doing wrong??? Please help.

Hmmm. I worked a lot with TIA 10.5, TIA V11+SP2.
And when i tried to install V12, I had many many problem so I decided not to install V12 at all, but wait for V13.
After short time (Significant?), TIA V13 was published.
And there are no communication problem.
Suggestion - if possible, switch to V13+SP1.
Also, upgrading FW will help. S7-1500 (like S7-1200 in V10.5, V11) were pretty buggy at that time.

With TIAP V13, for a year and longer, I have no problem or seriuos bugs.