This must either be changed in both client and server to AES-256-GCM, unless the workaround (data-ciphers-fallback AES-256-CBC) to force it to accept the CBC cipher server-side is deployed in the ovpn file Here is my working config for this setup where its a new 4096bit file, using a AES-256-CBC encryption server ( Firewall side)

In limited testing with OPVN 2.6.0 on windows, I confirm, with an updated (4096bit) client certificate the line providers legacy default still needs to be present, a bigger issue is for my setups is the default cipher AES-256-CBC. Probably wrong password or unsupported/legacy encryption 14:35:40 us=328000 Need hold release from management interface, waiting. Brand new Community OpenVPN client Version 2.6.0 ( Community Downloads | OpenVPN) fails to connect and shows these related messages in log, whereas previous Version 2.5.8 connected flawlessly, - any ideas/suggestions from other users what to change (serverside/clientside)? 14:35:40 us=328000 OpenVPN 2.6.0 Windows-MSVC built on Jan 25 2023

OpenVPN Client 2.6.6 for ios instal