I had the same issue, make sure that steam is online and run the dayz from steam window button, in my case that was the answer

Hello EnVizsion,

Something must be disrupting your connection to the servers, and unfortunately, this is something that we cannot fix from our end. Please refer to the network troubleshooting guide below:

1. Check all the physical devices on your network to ensure they are plugged in and powered on.
2. Perform a connection test on each device connected to the network. For reference, here is a list of platform-specific troubleshooting guides:

http://windows.microsoft.com/en-us/windows/network-connection-problem-help#network-problems=windows-7&v1h=win81tab1&v2h=win7tab1&v3h=winvistatab1&v4h=winxptab1

NAT Types:

• Open
• Moderate
• Strict

Open NATs can connect to any of the three types. --> Probably the least common type
Moderate can only connect to open and moderate. --> Probably the most common type
Strict can ONLY connect to open.
Strict NATs are a difficult problem with peer-to-peer games. Since most people don't have open NATs, the player with a strict NAT won't be able to find many joinable games.

Also, if the player with a strict NAT does manage to join a game, if another player with a moderate NAT joins later, the player with the strict NAT gets kicked out.

Another problem is that sometimes the ISP (Internet Service Provider) is also behind a NAT, which often means even if you have a direct connection to the internet (without a router/firewall), the ISP still acts as a strict NAT.

Port Forwarding:
The following Ports need to be open on your router to connect to the online servers:
TCP 80, UDP 88, UDP 2302, UDP 2314, UDP 2326, 2338

If you need assistance with opening these ports, please refer to the following website for more information (you will need to know your router brand and model, as the website guides are based on specific routers)
http://portforward.com/english/routers/port_forwarding/routerindex.htm

Here are some additional tips that have helped many players improve their connectivity:

1. Make sure your router's firmware is upgraded the latest version (very important).
2. Unplug your router for 10 minutes and plug it back in. Some older routers degrade in performance over time until it is rebooted, similar to a PC.
3. Disable any firewall or other network filtering for the game.
4. Enable uPnP (universal plug and play) on your router.
5. If you don't care about security, enable DMZ (de-militarized zone) on your router for your PC's address. This turns off all of your router's firewall features for that specific PC.
6. Run 'cmd' in administrative mode and use command ipconfig /flushdns
7. Contact your ISP and ask them what your DNS setting should be.

Direct Connection:
If you are still having issues connecting to the online servers after trying the above steps, try connecting your broadband modem directly to the console or PC you are playing the game on. This can help determine if the issue is related directly to the router or another source.

Alternatively, you can try out the following steps:

1. Start Steam and right click on DayZ in your game library (make sure that the game is not running).
2. Select the tab labeled "Local Files".
3. Click on the button labeled "Verify integrity of game cache...".
4. Restart your pc once the process is complete.

After this, do the following.

1. Hold down your Windows key and press R.
2. Type in "cmd" (without quotation marks) and hit Enter.
3. Type in "netsh winsock reset" (without quotation marks) in the command window and hit Enter.
4. Restart your pc as/if prompted by the cmd window.
5. Launch DayZ.

If this does not solve the problem, here's a suggestion that is a bit more drastic. Please be aware though; you might have to reinstall your other Steam games afterwards:

1. Move the entire "C:\Program Files (x86)\Steam\SteamApps" folder to your desktop. Your "SteamApps" folder should now be at the following location: "C:\Users\<username>\Desktop\SteamApps".
2. Move the "DayZ" folder out of the "C:\Users\<username>\Desktop\SteamApps\common" folder and subsequently delete the "DayZ" folder.
3. Uninstall Steam while making sure the "SteamApps" folder is still on your desktop.
4. Restart your pc.
5. Install a new version of Steam.
6. Go to the new "C:\Program Files (x86)\Steam\SteamApps" folder.
7. Move everything inside the old "SteamApps" folder on your desktop to the new "C:\Program Files (x86)\Steam\SteamApps" folder.
8. Install DayZ again.

Regards,
JStewart