Can't access select https website behind ubuntu server

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http://serverfault.com – We have a problem accessing an HTTPS site, it only happens to only one HTTPS site other corporate HTTPS sites are accessible behind the ubuntu server with ip /29. I tried connecting my laptop directly under the ISP modem with IP /29 and I can access the affected HTTPS site but if I'm behind the server I can't. IP forwarding is enable on the server, eth2 is masqueraded and eth0 accepts all traffic Access to the HTTPS site was ok until two weeks ago where we started to have a problem. I can't remember making any significant changes on the server to have disabled access to (HowTos)