video call suspend

Hi：

My Openfire env like this:

openfire  3.9.3  on  server  centos 6.5

spark 2.6.3 on client win7 / win8   , x86_64

redfire   redfire-370-0.0.06 

The problem is , when  I use video call ,  client will suspend . 

Thanks for any advise。  By the way , where can I download spark  2.5.8  ?