Relaying a message from the team here at DICE:

UPDATE #3 (Nov 4):
Fixing server crashes
New server update (R6) was rolled out across all platforms to fix the most common server crash.

UPDATE #2 (Nov 3):
Fixing the server queues on PC
We're rolling out a server update on PC with a fix for the join queue. As this new server version starts to populate servers, you will notice that server queues on PC will be available again in Battlefield 4. Note that it might take some time before the majority of PC servers are equipped with this fix (up to 24h).

UPDATE (Nov 3):
Server crashes
We have identified an issue where the game server will crash and disconnect players, causing them to lose any stats gathered during that specific round. We have a fix in progress to address this issue in a server update and will let you know once it's ready to roll out.

Since the launch of Battlefield 4, some fans playing online have been experiencing various issues with the game. Thanks to your feedback, many of these problems have been resolved, but there are still a number of bugs that we are actively working on. Below you will find a list of some of the resolved issues, as well as some of the issues we are prioritizing at the moment and what we're doing to address them.

Game crashes and freezes
ELIMINATED AS WE IDENTIFY THEM
Players on all formats have been experiencing game crashes and freezes while playing. We have logs of the most frequently occurring client crashes, and we are actively working to Obliterate the cause of these crashes in upcoming updates.

Note that crashes come in different types, and therefore this is technically not one single issue. There are two kinds of crashes and two types of updates that can address them: server-side updates that we can release on the fly (four of these have already been released since launch), and game client updates that require more in-depth testing and certification before they can go live.

We have found and eliminated some of the server-side crashes on PC in the latest server update (version R4) that went live November 1. There is also a planned client update on PC in the near future where we are aiming to eliminate as many of the client-related crashes as possible.

Progress in Multiplayer Lost
INVESTIGATING
Players have reported losing their progress in multiplayer. This is probably related to crashes stopping the game reports from being sent to Battlelog. We are still investigating this issue in more detail. Note that your progress sometimes can seem to be reset during server maintenance windows. In these cases, your stats will be just fine and reappear later.

Single Player Save File Corrupted
INVESTIGATING
We are still investigating the issue of single player save files being corrupted for some players. If you have experienced this problem, please describe below the steps leading up to the save file being corrupted, your platform (PC, PS3 or X360), and when the issue occurred. If you're on PC, please also list your OS and system specs.