My iPhone doesn't hold a Wi-Fi connection anymore?

My iPhone 4S connected to my household Wi-Fi perfectly for about 8 months now and today it just stopped being able to connect to it. All the other devices in the house connect perfectly so it's not the actual connection, it's the phone. When I turn it off then on it connects to the Wi-Fi but after about 10 minutes it loses the connection and goes back to 3G networking which is extremely slow (thanks, Vodafone) and I need Wi-Fi for a lot of things during the day! Can anyone help please?

Try to go to network settings and play with it a little, this happened to my friends phone his phone was connected to 4g so be sure to turn that off

Attempt #1:
1. Go into Wi-Fi settings and DELETE the existing wireless settings/account.
2. Add the account back onto the phone while not very far away from the router.
3. Venture away from the router and see how your signal strength holds up (it could be something "new" in your environment causing weak spots in your signal)
*. If the problem is corrected - you're done.

Attempt #2 and #3:
1. MANY people end up damaging their wireless "radio" connection from inside the unit (as well as the bluetooth) by knocking their phones around and/or SITTING on them (back pocket storage) and because there are different variations of models for each physical release, this may or may not apply to your device…
2. Power off the phone, remove the battery cover and remove the battery.
3. Look at the plastic back of the phone toward the center/bottom-center of the phone's back cover and see if there are little copper "pads" - if so, they're about 1/4" wide/tall each and very visible.
4. If they exist, using a Q-Tip and rubbing alcohol, clean these pads. (For some models, the "antenna" is actually taped on the back cover of the phone and these pads connect the phone TO the antenna.)
5. If your unit has these pads and the antenna itself is torn/mangled, you'll need a replacement - fixing the copper "sticker" isn't really an option worth venturing.
6. Even if you do not have this type of antenna, leave the batter out of the unit for approx. 3-5 minutes - this will "reset" the units radios and they'll readjust when the unit is put back together and turned back on.

Attempt #4:
1. If the above steps are fruitless, there's two options left… Physical damage or software damage.
2. PHYSICAL… Get service, there's not much you can do personally.
3. SOFTWARE… Run a factory reset and force the phone back into it's initial settings.

If the software is corrupted or a recent update screwed things up for you, back up all your files you want to keep and wipe it clean, test out your wireless connection and of everything "feels right" again, reinstall your files, apps, etc. And you're done. If a factory wipe doesn't cure it, there's physical damage.

Warnings:
1. "But Dialing" (leaving your phone in your back pocket) is hard on the unit - many people just break the screens this way… But circuit boards INSIDE these things have been found from time to time literally split in half. It's a bad habit - one to break if you have it.
2. Purses… I've seen more dead phones because of little metal objects being lodged into USB, headphone and accessory ports than anything… And it's almost EVERY time based on Purse Pollution. If you store your phone in the catch-all… Seriously consider a skin that completely covers the phone AND all of its openings.
3. Wetter is Better… Getting things INSIDE the phone is normally left for purses and junk drawers, but water is a beast we're all prone to. The earpiece and microphone "holes" are the most vulnerable - water itself isn't harmful… But contaminants IN the water can destroy most anything inside.
All three items listed here can easily damage the radios (Wi-Fi, bluetooth and the main cell transceivers) - just food for thought.

Hope this helps and good luck!