VPN & Internet Banking

“Using VPN I get an error code when opening internet banking and I have to disconnect VPN in order to use internet banking - why?”

Without more information it is not possible to tell.

Ask your bank.

I contacted the bank first, and they said there is no problem at their end, it must be the VPN, especially since online banking works OK if I disconnect from VPN.
This is the error message:
Sorry, an error has occurred [Error: 1007 ID: 18.71476768.1493200051.5989194]

Contact support: https://support.avast.com/support/tickets/new

I don’t understand how VPN works, because neither I as user nor the corresponding bank, broker, tax service, etc is provided with a password that
ONLY I AS USER and the ONLY THE RECIPIENT KNOWS.

VPN can only be as safe as the standard password the VPN provider uses, and even then it seems that my data must be leaving my computer unencrypted, and is only encrypted by the VPN provider when it gets to the VPN provider, and likewise, since the recipient (bank, etc) does not and cannot know the password the
VPN provider is using, the data necessarily must be decrypted BEFORE it arrives there (or else they could not read it.)

I believe that with regard to, for example, a tax return being filed electronically, a safe system has full encryption on my side, and decrypts only when the data safely arrived on their side, because they know both my and their own password.

If someone could explain the error of my way of thinking on this, I am all ears. Until then I’ll continue to believe that VPN is not as safe as advertised.
Thank You!