Everytime I connect my phone to my wifi after a while it disconnects and won't work until I put the password again, reboot the router, or link the device via WPS. I'm desperate I can't even use my own wifi. You people seems the most reliable since every answer I got didn't work, so if the question doesn't belong here please just help me out and I will delete it.
Get a reputable ethernet router (one which can run DD-WRT is a good bet), and connect the WAN interface from your Tim AG combo to it. You may also need to change the LAN subnet on one of the devices to a different range so as not to have conflict). Disable WIFI on the Tim AG combo if you can.
Your problem is most probably a combination of compatibility issues between devices - new routers, and routers with a greater number of users typically iron out most of these problems. (I could be doing it a disservice, but my guess is your provider has rebranded a cheap-as modem/router to keep their prices down, and you are paying the cost - I could not find ANY English references to it, and the pictures don't inspire confidence of a well made product designed for WIFI - for example no decent external aerials)
Otherwise complain to your ISP that there router is not doing the job you are paying for !