What make me suspitios is if i check the SD card there is the db.php not in the www-folder. Should it not be into the www folder to process php?
Doesn't matter.
Testing method:
Step 1;-
opkg update
opkg install mysql-server //only use client portion
Access MySQL Server From The Shell Prompt (Command Line)
http://www.cyberciti.biz/faq/how-do-i-access-mysql-server-from-the-shell-prompt-command-line/
Use Mysql Command Line to test server and network.
Step 2;-
Run
/mnt/sda1/db.php 80
at Shell Prompt, and use step 1 to confirm data in the DB.
Step 3;-
Put code into Arduino test again.