[PC] "You have lost connection to the session" on loading new map

I have the same issue. But I only thought of two reasons as to why this is happening. First is forwarding ports. I haven't tried forwarding the ports from the official EA article yet ( https://help.ea.com/en-us/help/battlefield/battlefield-1/battlefield-1-troubleshooting/#Ports ), but I doubt it will help. If the problem was blocked ports, we probably wouldn't be able to connect at all to any server. So my second theory is a slow hard drive. I don't know if your game is installed on a HDD or SSD. If it's on a HDD please check the model. Because my game is installed on a hard drive with 2TB of space, but only 5400 RPM speed ( standard speed is I think 7200 RPM). This slow hard drive really affected loading times on other games, for example Rainbow Six: Siege (I was always the last person to load in a match). So I thought that during loading, the game occasionally freezes, and if it freezes for too long, the server assumes you crashed, and it kicks you out. I don't know if this happens to you, but before I get the "You have lost connection to the session" error, the game freezes at the loading screen for about 5-10 seconds. Thats why I  think it's a problem with my hard drive. Everything is mostly a theory really. I have no clue as to why this happens. I will try playing with the settings and if I find any solution, I will post it here. Sorry for not helping too much, I only found two threads with this problem and both have no solutions.

I tried forwarding the ports, but it didn't help. 

I have a SSD myself, so that should not be the problem either.

Thanks for the reply though. Did you notice it happening on certain maps more then others as well? 

Yes! That seems to have solved the problem! No problems tonight. Thank you!

bump. never ever had DX12 on. I have forwarded every port we've been provided with, I am wired to my router so distance isn't the problem, internet connection is decent (250Mb), reinstalling doesn't work, since I recently reinstalled win10. FPS could possibly cause the probem since it has some kind of connection with recieve rate. As soon as you drop below 48FPS, your rcv rate will drop to 30Hz. I have to say this is a bump as well, because I had the same amount of FPS ever since I bought the game, and it only started to happen since the spring update. If I have to take a guess the netcode change was responsible for this issue, because it came with the spring update if I'm not mistaken. I really need a fix, or a simple answer why I cannot play this game. I didn't pay to be in the main menu every 5 minutes, I want to have fun without me counting the minutes on how much time I have left before I get kicked again.

I am also experiencing the same issue. I have tried with or without DX12. Port forwarding has not changed anything. I play on a ssd. reinstall/repairing didnt change anything and I've done everything the help article for PC suggested doing. My fps is pretty much always in the 100s. waste of $100 to get deluxe.

Where do you deactivate the DX12 in the advanced video option? I cant see it on my BF4

They're talking about Battlefield 1, not 4.