Some months have passed any update in the Netflix app 15001 issue?
Just asking because I have the exact same issue on an Huawei P20 Pro (CLT-L29) EMUI Build-Number 9.1.0.370 bootloader locked, no root, widevine CDM L1, Google play protect says Device is certified, banking apps, Google pay, amazon video, deezer etc. all working fine inkl. downloading drm stuff. Only Netflix does open with this network issue 15001 and Google play movies does not download movies. playing movies just works fine.
Have tried all the tricks which play services, play store, cache partition, app caches, reinstall. The last thing I will do is a factory reset.
I have a second exact same Huawei P20 Pro device (only different color) which just works fine.
What could be the issue?