@ovcijisir
Here is my experience when trying to create wallets on airplane mode on Blocksktream Green and Blue Wallet.
Blockstream Green:
The app asked for my biometrics (fingerprint) at the beginning of the setup process. I had two options: to provide it by touching my fingerprint sensor or click the "Cancel" button. I clicked cancel and entered a 6-digit PIN code instead. The software started creating the wallet but it failed and I saw the "Network error" message you mentioned. I tried two more times and got the same error.
Then I went back to the beginning and provided my biometric data. Blockstream Green generated the wallet immediately. So, if the software gives you the option to provide your biometrics to unlock it, you should provide it. That's what worked for me.
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Thank you for feedback Pmalek! I never share biometric data, so that is almost certainly the cause of my issues. I was wondering why other people could generate wallet offline without any problems while I couldn't.
Ill try to generate new wallet with biometric data allowed on another phone later and send feedback regarding results.