I live in China so I have the luxury of testing this. I have a shop page where you can click to show a reward ad in exchange for game cash and the button is greyed out if the ad has not loaded yet. If I activate the VPN server on my device the ad loads pretty quickly and is thus greyed after a few seconds or so. But with VPN disabled the ad still is not ready after several minutes.
The log gives this error:
[Appodeal 1.3.6][error] Error while fetching ad queue for "Rewarded Video" request: Error Domain=com.appodeal.error Code=195944099 "Got error while fetching ad items from sever" UserInfo={NSUnderlyingError=0x15eb5480 {Error Domain=NSURLErrorDomain Code=-1001 "The request timed out." UserInfo={NSErrorFailingURLStringKey=https://api.appodeal.com/get, \_kCFStreamErrorCodeKey=-2102, NSErrorFailingURLKey=https://api.appodeal.com/get, NSLocalizedDescription=The request timed out.,
I have other apps in China on the app store using Admob and the ads show no problem at all.