DLNA communicates using HTTP (correct?) which is now banned by Apple's new policy.
See: Transport security has blocked a cleartext HTTP
You could set the settings in .plist file as advised above but that would require that you know all the hosts where the DLNA server listens to. I also believe that you can not change the .plist on the fly.
Can you easily switch DLNA server to run on httpS? Is this a "standard" feature?
What is your recommendation for this problem?
BTW, would you have a good tip for DLNA C++ client with reference implementation?