On my Red Hat server, the sshd will not accept my correct certificate login. However, If i start another sshd on another port, it works! (I assume the second sshd loads the same configruation files.)

second sshd started with: sudo /usr/sbin/sshd -p 54321 -d #-d is optional and prints debug output

ssh strange-host -p 22 -vvv prints:

debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Offering public key: /home/me/.ssh/id_dsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug3: Wrote 528 bytes for a total of 2389
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password

ssh strange-host -p 54321 -vvv prints:

debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Offering public key: /home/me/.ssh/id_dsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug3: Wrote 528 bytes for a total of 2389
debug1: Server accepts key: pkalg ssh-dss blen 433
debug2: input_userauth_pk_ok: SHA1 fp 0f:1c:df:27:f7:86:49:a8:47:7e:7f:f3:32:1c:7d:04:a3:73:a5:72

So the question is why the difference?

I have thought of no way to get any helpful logging from the "standard" sshd to troubleshoot the problem.