I have quite a lot of Mikrotik routers (various models) set up as openvpn servers with no issues.
Today I set up a CCR2004 with fw 7.17.2 as I did for the others.
I have connected to it from my Linux client, and got a lot of errors like this: AEAD Decrypt error: cipher final failed
I have run some tests and I have discovered that using AES-256-GCM causes this. Using AES-256-CBC works fine.
I suppose it might be related to this change log I found in 7.18.rc3, that states:
ovpn - disable hardware accelerator for GCM on Alpine CPUs (introduced in v7.17)
I leave this post here hoping to help someone else. If you see these errors, use CBC instead of GCM. (Or use a firmware 7.16.x or 7.18.x)
