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Can I connect to Stanford university using SLAC VPN?
Yes, Stanford supports the SSL protocol. Instead of connecting to "vpn.slac.stanford.edu", connect to "su-vpn.stanford.edu". You should use your SUNetID and password rather than the SLAC Windows password.
When connected to the SLAC VPN, Stanford university is using different VPN protocols and technologies, so the SLAC VPN client can't be used to connect to Stanford through VPN. But when connected to SLAC VPN you can reach Stanford ressources as if you were in your office at SLAC.
If you are a SLAC employee/user willing to access SLAC ressources you should use SLAC VPN, if you are a Stanford university employee/student you should use the Stanford VPN client provided on http://itservices.stanford.edu/service/vpn.
Issue connecting to SLAC vpn gateways with Samsung Galaxy devices
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Then if you try to go to https://vpn.slac.stanford.edu or if you try to connect to the SLAC VPN gateways with the cisco anyconnect client it will work without issuing a warning.