We have a Wordpress based website (rendeljkinait.hu), and we face freezing issues while editing articles when using Chrome. When I hit the save button for the 7th time without page reload, the article editor freezes during save and I get "waiting for available socket" error in Chrome. No matter how long I wait, the editor won't save until I reload the page. When I'm using Firefox, everything is fine, no matter how much I hit the save button. Current Wordpress version is 5.2.3, but error occured in former versions too.
I investigated the error, and found it is caused because Chrome never closes the open sockets until I reload the page. So until hitting the button 6 times everything is fine, since Chrome and other modern browsers allow to have maximum 6 paralell connection to a single host. But after I press the button for the 7th time, there is no space for another connection, so Chrome is waiting for the older connections to get closed, but it never happens. Here's a screenshot from net log
Using Firefox I observed that it always closes the connection after the save is successful, so only 1 connection is active all the time, it never exceeds the 6 paralell connection limit. I attached Chrome netlog file here, you can view it here. I also attached a video showing Firefox closing the connection here (107.6.*.** is our servers IP).
For various reasons we have to use Chrome, so I would like to find a solution for this problem, but I'm completely stuck. Does anyone have a suggestion what could cause the problem and how to solve it? Thanks in advance!