Error getting https Index (custom https repo)

Hi I created a custom repo for fdroid. If I add the repo via http there is no problem, but if I add the repo via https I get "Error getting index file form https://sparber.net/fdroid/repo All other repos didn't create errors."

After I change the address to http://sparber.net/fdroid/repo and press update and go back to https://sparber.net/fdroid/repo it seems to work.
And also when I what few minutes, fdroid finds the index file. That above doesn't seem to be always true.

I tried some other repos:
Those doesn't work:
https://s3.amazonaws.com/storymaker/fdroid/repo
https://sparber.net/fdroid/repo
They worked:
https://markwinter.me/fdroid/repo
https://f-droid.i2p.io/

My Phone: Galaxy Nexus CM12.1 beta (I tried on a other phone too, just I don't have any infos of that phone)
Fdroid: 0.83

I/Timeline( 5372): Timeline: Activity_windows_visible id: ActivityRecord{a6eb8a1 u0 org.fdroid.fdroid/.views.RepoDetailsActivity t419} time:3636955
I/FDroid  ( 6103): Updated repo. Notifying provider change: 'content://org.fdroid.fdroid.data.RepoProvider/7'.
V/WindowManager( 5372): not Base app: Adding window Window{2b0f3f4c u0 Please Wait} at 10 of 16
D/FDroid  ( 6103): Unscheduled (manually requested) update
I/org.fdroid.fdroid.net.HttpDownloader( 6103): Downloading from https://sparber.net/fdroid/repo/index.xml
D/org.fdroid.fdroid.net.Downloader( 6103): Downloading from stream
E/FDroid  ( 6103): Error updating repository https://sparber.net/fdroid/repo: Error getting index file from https://sparber.net/fdroid/repo
E/FDroid  ( 6103): org.fdroid.fdroid.updater.RepoUpdater$UpdateException: Error getting index file from https://sparber.net/fdroid/repo
E/FDroid  ( 6103): 	at org.fdroid.fdroid.updater.RepoUpdater.downloadIndex(RepoUpdater.java:115)
E/FDroid  ( 6103): 	at org.fdroid.fdroid.updater.RepoUpdater.update(RepoUpdater.java:148)
E/FDroid  ( 6103): 	at org.fdroid.fdroid.UpdateService.onHandleIntent(UpdateService.java:370)
E/FDroid  ( 6103): 	at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:65)
E/FDroid  ( 6103): 	at android.os.Handler.dispatchMessage(Handler.java:102)
E/FDroid  ( 6103): 	at android.os.Looper.loop(Looper.java:135)
E/FDroid  ( 6103): 	at android.os.HandlerThread.run(HandlerThread.java:61)
E/FDroid  ( 6103): Caused by: java.io.IOException: Hostname 'sparber.net' was not verified
E/FDroid  ( 6103): 	at com.android.okhttp.Connection.upgradeToTls(Connection.java:205)
E/FDroid  ( 6103): 	at com.android.okhttp.Connection.connect(Connection.java:155)
E/FDroid  ( 6103): 	at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:276)
E/FDroid  ( 6103): 	at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:211)
E/FDroid  ( 6103): 	at com.android.okhttp.internal.http.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:382)
E/FDroid  ( 6103): 	at com.android.okhttp.internal.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:332)
E/FDroid  ( 6103): 	at com.android.okhttp.internal.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:199)
E/FDroid  ( 6103): 	at com.android.okhttp.internal.http.DelegatingHttpsURLConnection.getInputStream(DelegatingHttpsURLConnection.java:210)
E/FDroid  ( 6103): 	at com.android.okhttp.internal.http.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:25)
E/FDroid  ( 6103): 	at org.fdroid.fdroid.net.HttpDownloader.getInputStream(HttpDownloader.java:51)
E/FDroid  ( 6103): 	at org.fdroid.fdroid.net.Downloader.downloadFromStream(Downloader.java:123)
E/FDroid  ( 6103): 	at org.fdroid.fdroid.net.HttpDownloader.doDownload(HttpDownloader.java:99)
E/FDroid  ( 6103): 	at org.fdroid.fdroid.net.HttpDownloader.download(HttpDownloader.java:64)
E/FDroid  ( 6103): 	at org.fdroid.fdroid.net.Downloader.downloadUninterrupted(Downloader.java:111)
E/FDroid  ( 6103): 	at org.fdroid.fdroid.updater.RepoUpdater.downloadIndex(RepoUpdater.java:102)
E/FDroid  ( 6103): 	... 6 more
D/FDroid  ( 6103): Not checking app details or compatibility, because all repos were up to date.
D/FDroid  ( 6103): Update took 0 seconds.
D/FDroid  ( 6103): Invalidating preference 'lastUpdateCheck'.

I tried to update view minutes later (around 4 min) The error is now gone. Logcat output:

I/org.fdroid.fdroid.net.HttpDownloader( 6103): https://f-droid.org/repo/index.jar?client_version=0.83 is cached, so not downloading (HTTP 304)
D/FDroid  ( 6103): Repo index for https://f-droid.org/repo/index.jar?client_version=0.83 is up to date (by etag)
I/org.fdroid.fdroid.net.HttpDownloader( 6103): Checking cached status of https://sparber.net/fdroid/repo/index.xml
I/org.fdroid.fdroid.net.HttpDownloader( 6103): https://sparber.net/fdroid/repo/index.xml is cached, so not downloading (HTTP 304)
D/FDroid  ( 6103): Repo index for https://sparber.net/fdroid/repo/index.xml is up to date (by etag)
D/FDroid  ( 6103): Not checking app details or compatibility, because all repos were up to date.
D/FDroid  ( 6103): Update took 1 seconds.
D/FDroid  ( 6103): Invalidating preference 'lastUpdateCheck'.