IP address 192.168.0.26 is on your local network. The other sites you connect to are most likely out on the internet.
When you power on your b2, an IP address is most likely "assigned" to your b2 by your wifi router. Unfortunately, your router might assign a different address sometimes! That means that you need to check the display on your b2 each time you start it to see what address has been used. Did you do so the times you were unable to connect?
To fix this, you might be able to setup your wifi router to always assign the same address. You have access to your router's setup (typically a web page available at somewhere like 192.168.0.1) and then figure out how to have it assign static IP addresses to specific MAC addresses. Alternatively, it might be possible to hack the Pi's Linux setup to use a fixed IP address. I've just started looking into how to do that.
Tony