possible corrupted default?

[Jackson Chan]

My DNS-320 rev A has 2 problems:

1)it shows only 100mb/s

2)no dhcp with default setting.

Here is the detailed symtoms:

It had original firmware 2.05. It got assigned IP from router's dhcp daemon with NO problem. 

After installing alt-f 1.0, it rebooted but it can no longer get ip from dhcp. 

Under serial console, I saw it failed and got itself a fixed ip 192.168.1.254. When I login via web on 192.168.1.254 and it will ask me to configure the network and manual was the default, IF i change to DHCP here it WILL receive the IP from dhcp OK. If I clear the setting, it will once again fail to get ip from dhcp.  

I tried to revert back to original firmware 2.05, dhcp works fine again, switched back to alt-f and dhcp failed. Obviously this is not cabling issue. 

When I could access the web, I only saw that its speed is only 100mb/s

What's going on? I have another DNS-320 rev A and the behavior is different(which is correct as it will auto get ip from dhcp).

Is this a possible corrupted default? How can I troubleshot this?