Wifi drops, not internet but signal is still 5/5

Howdy,

My computer is working on Mac OS X, 10.7.5. It is a 2.7GHz Intel Core i5 from May 2011.

Since last week, I have been experiencing strange things with my Wifi.

The configuration in my home is: the internet box/router is on stage below, my iMac being upstairs. Unfortunately, it can't be changed :/

The problem is the following: from time to time, sometimes fifteen minutes sometimes one hour apart, suddenly internet drops. If I am watching a video it stops, if I am voice chatting I can continue to hear my friends but can't talk, if I am surfing on the web it displays simply "you are not connected to the internet".

However, my wifi signal stays at 5 on 5.

Except from that, internet is really fast and comfortable.

My solution is to desactivate my wifi and then re-activate it. Sometimes I have to select my home wifi network manually, but most of the time it catches it automatically.

It does the trick, but sometimes I have to "double the operation" to be back on internet.

I am the only Mac user at home, my roomates have PCs and they do not experience the same drops, I am the only one. One of my roomate plays a lot online and I would know the second there is a drop (screams!).

It is not a big handicap for most of my applications (I work at home), but for the hobbies on the computer it's killing me (I live abroad, so voice/video/normal chatting, I do play a little and enjoy watching videos when there is no freeze at the paroxysm!).

I have followed most of the basic stepsgiven in other threads, like reset box, deleting Keychain Access... and it did not prove efficient.

Just now I have tried to manually set my IP in Network > Wifi > TCP/IP. It's been good for 30 minutes now, but I have already experienced respites for a day or two and then... back in the activate/desactive routine. Plus, I don't believe in magic and my "pro network trick" of simply clicking manually and entered a randoom number at the end of my IP... it does not convince me 😝

Thank you in advance for any advice, help, for your time and for having read my message,

Regards,