strange....
first, i am confused why your ping is not shown on our server in your favs. first, i would delete our server and search it over the serverbrowser if you ping is shown when our server is of them in the list.
i have same equal prob with the connection lost. if i ghost with my laptop and lakaelo-lights account, bf4 is running and all is running well. then i go over to my officeroom, start the PC to ghost with my account too, then i can´t join and get always the same message as you ( in german ). same happend when i play here in my officeroom and my son nico will play too, he get the same message and can´t join. i have also a little message in the bottombar ingame talking about "...look if port 2334 is open" or something else.
normaly i restart our router and after that, we both can join.
i have no clue why this happend but my guess is, that there is too much traffic at this moment in my broadband ( wifey laptop and mobile, my mobiles, nicos mobile, Tv and some other stuff ). maybe some of them or all together blocking something the game needs. thats the only explanation for me, why it works if i restart the server because that means i kick everything else out before.
don´t know your living and if your have also other people using your inet and maybe you installed something new stuff which is using inet or wlan??
