gate brace clamp

I am looking for a corner rail clamp.

My upright post is 2 1/2 inches and the rails coming off if it will be 1 3/8

I found line rail clamps and end rail clamps online, but nothing that will allow two rails to come off of a center post at a 90 degree angle.
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There is no such fitting as a 90 degree line rail clamp. Unfortunately a fitting like this would not make a secure bond of the post and rails.