Disconnections immediate or every 10-20 mins
-Log into your modem / router.
-Turn OFF UPNP.

Firewall Blocking / etc
- Boot MSconfig in start.
Disable ur Firewall and AV if its a windows based one.
Disable any other process there that might affect u and reboot.

ECN Packets has been enabled by a Net Speed Tool
To fix this :
1. open a CMD prompt AS ADMINISTRATOR
2. type "netsh"
3. type "int tcp set global ecncapability=disabled"

ECN packets are Refused by EA.
These are FAKE packets to fool the connection.
Set BF3 PC in DMZ on your router.
-Note will expose the computer, and the PC will not be protected by the routers firewall.
-Make sure you have your windows firewall enabled.
-This should be a "last resort" measure.

*Credit goes to P1nchedNerve
(Just a note, I didnt think you could do this with origin like you can with steam, but apparently you can!)

eg) Edit each computers BF3 executable to include the " -port XXXXX" (as long as each PC uses a different port):
Computer A = "C:\Program Files (x86)\Origin Games\Battlefield 3\bf3.exe -port 10000"
Computer B = "C:\Program Files (x86)\Origin Games\Battlefield 3\bf3.exe -port 10001"
Computer C = "C:\Program Files (x86)\Origin Games\Battlefield 3\bf3.exe" -port 10002"

Cause: Bug with x64 OS:
Fix: Open / Run regedit.
Navigate to: HKEY LOCAL MACHINE/SOFTWARE/WoW6432Node/EA Games
Change the GDFBinary & InstallDir paths to C:Program Files (x86)Origin GamesBattlefield 3
Try to launch the game and join game servers, and it should work./p>

-If you need help with making exceptions on your firewall(s). Consult the manufacturer.
-If you need help with portforwarding. Please visit www.portforward.com
-If you have problems or other issues portforwarding, contact your router manufacturer.

PC Ports:
TCP: 80, 443, 9988, 20000-20100, 22990, 17502, 42127
UDP: 3659, 14000-14016, 22990-23006, 25200-25300

PS3 Ports:
TCP: 80, 443, 9988, 10000-10100, 17502, 42127
UDP: 3659, 14000-14016

Xbox 360 Ports:
TCP: 53, 88, 3074
UDP: 53, 88, 3074

- Either caused by EA or hosting datacenter. No fix currently.
Update: Developers are working on the issue.

*For server admins:
-Highway Tehran is a really laggy map. Just about every 64p is having performance issues on this map.Cause is unknown.
Best idea is to take the map OFF the rotation if possible.
-This also applies to Caspian Border

Cause: A few players are experiencing this.
It is a server related issue. There is no fix.
Have to wait for the developers..

Fix: Open PROF_SAVE_profile in notepad++ :
\Documents\Battlefield 3\settings\PROF_SAVE_profile

Change: GstRender.Contrast 0.500000
*Lower the setting to whatever feels right.

Fix: Turn Origin Off in game.
Settings > In Game > Enable Origin In Game.

1. Go here: C:\Users\YOU\Documents\Battlefield 3\settings
2. Open PROF_SAVE_profile with notepad++ (can download for free)
3. Change the following variables:

GstInput.MouseSensitivity 0.050000
1st one is the normal mouse sens. USE whatever you like, or keep it the way it is.
These can be edited and it may solve the problem.

GstInput.Scheme0Sensitivity 0.000000
GstInput.Scheme1Sensitivity 0.000000
GstInput.Scheme2Sensitivity 0.000000

We are unsure of its validity, but if correct, it may be incredibly useful for players.
Battlefield 3 Weapon Database

1. Disable Origin's overlay (click the gear/cog and go to the "in game" settings tab).
2. In Steam, add Origin.exe as a non-steam game to your library.
3. Launch the Origin shortcut from your Steam library, then launch BF3.

Is affecting many users, even those with HDDs in raid 0.

Fix:
Try: Open / Run: regedit.
1. Navigate to: HKEY LOCAL MACHINE/SOFTWARE/WoW6432Node/EA Games
2. Change the GDFBinary & InstallDir paths to C:Program Files (x86)Origin GamesBattlefield 3
3. Try to launch the game and join game servers, and it should work.
4. Alternate Fix: Buy a SSD drive, install BF3 & origin on there.

Alternate Fix: Buy a SSD drive, install BF3 & origin on there.

1) Update to LATEST Nvidia Drivers
2) Turn OFF - AA - DEFERED
3) Turn OFF - VSYNC
4) Turn OFF - Motion Blur

1. Go to your card manufacturers website. (E.g. Gigabyte, MSI, Asus etc)
2. Select your card type (E.g. GTX 560Ti)
3. Download the latest BIOS for the card
4. Flash it (Install, it's usually an .exe file)
5. Reboot (Most will prompt you to do it automatically)
6. Frag away.

..with BF3 still running in background (possibly other AMD gfx cards too)

1. Load up single player.
2. Under options disable Anti Aliasing ( AA deferred )
*Best to disable AA post as well.
3. Download the LATEST drivers from your laptops manufacturers site.
4. Save & exit.

Multiplayer should now work. The game shouldnt crash to desktop.

-All credit to MrPaulieC

PROBLEM: Crashing at the end of every round (BF3.exe has stopped working) just before the scores come up and not being able to play single player.

SOLUTION: If you own an ASUS card (ATi or NV) and you installed the 'Smart Doctor' and/or 'ASUS Gamer' software then this is what's VERY likely causing you end of round crashes. All you need to do is uninstall Smart Doctor and ASUS Gamer, restart your computer and reinstall your video card drivers - that's it!!!

Cause: BF3 bug with onboard (motherboard) audio.

Fix: Install a separate soundcard & use that. Disable onboard audio in BIOS.
*Note users on EA UK forums have had success with Creative X-FI cards. (No game freezes)

Try setting the Origin.exe, BF3.exe and youre web browser .exe to "Run As Administrator".

Cause: Plugins / Network settings affecting Battlelogs operation.

Fix(es): Disable Adblocker, NoScript, Lower Firewall Settings, Open closed Ports, Enable / Disable uPnP.
Also disable any unnessesary plugins for your browser.
If all fails. Try a new browser.

Update: Users have reported lots of success with Internet Explorer 9.

Cause: C++ bug.

FIX: Uninstall both instances (if present) of Micrsoft C++ files on your system.
*These can be reinstalled later after BF3 is installed on the system.

1. Repair your Battlefield 3 installation. To do this, go into your Origin Client, right-click Battlefield 3, and finally click “Repair Install”.
2. Disable SLI or Crossfire (I know you arent going to like that !)
3. Disable anti-aliasing and filtering
4. Disable V-sync
5. Disable background apps, and turn off your anti-virus software

Press the Windows Key to force the game to Window Mode, click on the game window to go back into the game.
New settings should now be applied.
If this doesnt work. Try exiting the game and starting it again.

Update to the latest video card drivers.

Source

I found the solution for the problem with G73 from ASUS with ATI RADEON HD5series.
In fact you need to get a proper drivers from ASUS web site and not from AMD ....

Flash you graphics with "93vBIOSa.rar" .... find it on google.
Then deinstall ATI CATALYST preview install. CCLEANER DRIVER SWEEPER.

Install this release of CATALYST.
AND IT F........G WORKS!

And for info.... maybe you will find some more info.

*All credit goes to striker475

What does it help with?
This is not the solution for all crashes. It deals primarily with the crash to desktop that is caused by lack of virtual address space.Due to the unique nature of how addresses are mapped differently on each machine this crash may happen at different places and times of the game, even loading a map, menu or waiting on an AI turn. If you try this fix, and you follow directions properly, and it doesn't help you then your crash is due to something else.

How do I do it?
Follow directions explicitly. I have seen people consistently skip steps or not read the directions properly so it doesn't work for them whne they don't do what it says. it's not as complicated as it sounds, I'm just being thorough.

APPLY THE WORKAROUND (juicy caramel center)

Requirements
Only real requirements is that you have atleast 2GB RAM. You don't need beyond that even though we are allowing addressing up to 2.5 GB. Also following instructions and being somewhat familiar with working with files in windows is required. Make sure you are using Vista SP1 or later. If not then you need this hotfix that fixes a major blunder with Vista address space - http://support.microsoft.com/kb/940105 [support.microsoft.com]
That's all, follow the 3 steps.

1) Prepare the operating system to be able to use beyone 2GB address space with a userva of 2.5GB (only 32 bit OS's need to do this): I am purposely using only 2500 for userva for specific reasons and any more will likely not be needed, as a result the kernel will have plenty of space to play in.

Windows 7/Windows Vista
* In Windows 7/Vista go to Start menu. Go to Accessories. Locate the command prompt shortcut and hover mouse over it. Right Click on the shortcut then select Run as Administrator.
* In the command prompt type this exactly: bcdedit /set increaseuserva 2500. Then hit enter.
* Make sure you get a message back confirming the change was made. To verify the entry is there you can type just bcdedit, hit enter, and you should see the entry now listed.
* Then close the command prompt. You just told Vista to increase user virtual address (userva) space to 2500MB.
* Changes take effect on reboot but don't reboot yet.

SUMMARY
We extended the user virtual address space in XP, Vista and 7 to 2500MB, so now applications can utilize up to that much if they are set to be Large Address Aware. While some 32 bit games/applications are set, Empire is not.

2) Now reboot the PC because Windows needs to set the userva at 2500 which only happens after startup.
If you skip any step it will not work. When you have rebooted you should be good to go. Run the game as normal with the original game shortcut.

TO UNDO THE CHANGES
For Vista 32 Open command prompt as administrator and type: bcdedit /deletevalue increaseuserva. That deletes the entry.
Reboot and you are back to normal.

Open your console in BF3 " ~ " key.
Enter:
RenderDevice.ForceRenderAheadLimit 1
RenderDevice.TripleBufferingEnable 0

-Disable VSYNC.
*Ensure it is set to off on your graphics card.

Disable motion blur in your graphics settings.

*Affects Intel i5 & i7 CPUs with Hyper Threading.
*Possible fix for dual-core CPUs also.

Cause: BF3 Bug
Fix:
-In BIOS. Disable Hyperthreading.
-If you have a dual core CPU, manually set Affinity in task manager to 1 core.

Extra For AMD GFX users:
- Uninstall AMD CAP profiles (Make sure to uninstall the video driver also and clean the registry, reinstall driver when done.)

*Try updating drivers.

Nvidia Users download

AMD/ATI Users download

For windows7 32 bits users:
1) go to c:\windows\system32
2) scroll down and find PnkBstrA.exe or PnkBstrA application
3) right-click PnkBstrA.exe and choose Properties
4) click the Compatibility tab
5) click the button at the bottom of the window that reads "Change settings for all users"
6) click the checkbox for "Run this program as an administrator" and click apply and Ok

For Windows 7 64 bits users:
1) go to c:\windows\syswow64
2) scroll down and find PnkBstrA application
3) right-click PnkBstrA.exe and choose Properties
4) click the Compatibility tab
5) click the button at the bottom of the window that reads "Change settings for all users"
6) at the bottom of the window that reads "Privilege level"
click the checkbox for "Run this program as an administrator" and click apply and Ok

Cause:
Your version of PunkBuster and the Server's are not the same.

Fix:
Update Punkbuster and join an updated server. Send a message to whoever owns the server you keep getting kicked on and tell them to update their PunkBuster to the latest version.

Manual PB update tool can be found HERE.

There appear to be limited PB response messages to the player, or just that the developers got lazy.

If you get this message, either:
1) An admin has banned you because you have been bad (or the admin is just abusive).
2) It is displayed as the disconnected message for Idle timeout. <- IF you are that, then dont worry. You havent been banned !!!

Our recommended choice of server administration:
1. Procon. There can only be one
2. http://www.phogue.net/forumvb/forum.php

Alternative:
http://bf3cc.com/

1 .Country Kicker plugin for procon.
2. Auto kick players from far away countries to prevent higher pings.
3. Less high ping players = less lagging game.

Q: Why not just use ping kicker ???????????
A: What if we have people in our own country who get a ping spike ? We dont want them to be kicked !
Rather than running a ping kick. Lets just filter those who will likely have huge ping to us.

>Download & Install Instructions here<

First Partial Solution:
-Some maps are "bad" maps currently and cause/generate excessive lag compared to other maps.
-Try not to play these if possible.

"Bad" maps list:
-Caspian Border.
-Highway Tehran.

Second Partial Solution
-Currently 64p servers lag the most (no surprises there)
-Reducing player slots to 40 appears to reduce the lag by a fair amount. (No idea why 40 is the magic number...... I just report / relay this info.

...(so people can practice in jets and play around)

-This is for the BF3 server.
-Open startup.txt
-Change / enter in values in bold.

# How many players to start the round (int)
#vars.roundStartPlayerCount "8"
vars.roundStartPlayerCount 1

# Minimum players before a current around aborts (int)
#vars.roundRestartPlayerCount "4"
vars.roundRestartPlayerCount 0

Try to give it a reboot daily. Its a pain, and you may drop some busy gamers, but it will help prevent the lag.

-Try leaving the server settings on the DEFAULT settings.
*Yes its boring, and you probably wont want to do it. But it does help (at least in these early phases) to prevent your server crashing.