sorry to reply so late。
First most of our user are in China,
And i understandthe network setting that is different with other countries.
But i am very sure user didn't change any network setting in System Setting before he suddenly cannot access network.
You wrote:
user may recorver some hours later
Is this correlated with changes in connectivity, like a switch from WWAN to Wi-Fi or the reverse?
"recorver some hours later" means after no access to network happened, user may cannot use our app now, he then may use other apps or may don't use iPhone. And maybe several hours later, he picks iPhone, open app again, at that time he can use it again.
But i don't known whether they change network from WWAN to Wi-Fi or the reverse before he can use it again ( i ever confirm to our user whether he change the access setting in system setting page, the answer is no), i think the network change operation is very common, is that will be the reason to recover? if so , when no access to network happened, even user change network by click wifi icon to access byWi-Fi or not, he still cannot access network finally. (that are we confused why network disable suddenly...)
if some bugs happened in our app, the error code should not aways be system error, and even our custom socket connection connect failed, the system http connection should not be failed either。
One more question:
We also get some feedbacks, the network access control setting is already set to enable for all network(both wifi and wwan), but the app is still cannot access network.
We really don't known the right way to recover, each time we ask our user to reset network setting, reboot ios system and other operations, most of them can recover, please tell us the right way to recover.