Wrong "default Gateway" Coming At Reboot?

Hi all,
I am a recent 10.3 user, after having used 7.2, 9.0 and 9.3, which crashed a few days ago. .
I installed it almost successfully, I must say you guys at opensuse did a great job. Smooth install, no problems
Except this recurring one: At each reboot the "default gateway" (Yast ==> network ==> routing) jumps to some stupid 192.168.x.x address, when my network is in 10.10.x.x with 255.255.0.0 and the gateway is within this with 10.10.2.1.
I have to manually change it back to the right value: tedious!
Why so?
Any help welcome.
Best regards
Domi