Description of problem: Impossible to connect to servers that use old KEX algoritms If you try to connect to (for example) RDP server through a SSH tunnel and the SSH server uses only old KEX algorithm Remmina returns "Could not start SSH session. kex error: no match for method server host key algo: server [ssh-rsa,ssh-dss], client [rsa-sha2-256,rsa-sha2-512,ecdsa-sha2-nistp256,ecdsa-sha2-nistp521,ssh-ed25519]" while a ordinary ssh client is able to connects. I think is the same as: https://gitlab.com/Remmina/Remmina/-/issues/983
Remmina uses libssh for the SSH connection, have you tried to switch from the DEFAULT crypto policy? $ cat /usr/share/crypto-policies/DEFAULT/libssh.txt | grep Kex KexAlgorithms curve25519-sha256,curve25519-sha256,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512 This one above is from Fedora 33, the 34 one is a bit further restrictive.
Fedora 34 has the same output for the default crypto policy but previously, on Fedora 33, remmina worked with that server. However, if I set crypto policy to "LEGACY" it works :) thanks