cant connect to battle.net need new hashes

Mmm... What hashes? There is minor issue that if you try to manually update the game or move it as portable - it will lost the General server entry and old Bnet US West/US East/EU/Asia servers appear. Trying to connect to them will lead game get broken installment by trying to incorrectly apply latest patch that already included/obeolete. Restore General entry not solve this - need full reinstall.

Rarest games require non-portable installation. Very few for 30 years. GOG builds increase that amount. GOGs launchers require registry entries.
Original Wc2 not require registry and generate needed by next launch. GOG Wc2 Launcher require registry and new General server require that. Game store original Bnet 4 servers inside some conf file in one of MPQ archives. "General" server adress ("gateway") stored in setup file only. So if game detect no entries it generate new from MPQ and make online function useless and then trying to connect make installation broken.

GOG/Bnet(modern) versions not compatible with old Retail 2.02.

Uninstall game and make sure no entries left.
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There was also major issue that GOG lost Bnet Multiplayer keys. Happened few times. If you get error message at Key page of the game - contact GOG and/or Blizzard support.
Go to WEBSITE version of your GOG account Library - game page - MORE - Key.

https://support.gog.com/hc/article_attachments/360019904578/War222.gif