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Yes, as all your traffic will be then routed through the VPN tunnel making you appearing from a different IP address to the server.
Only persistent connections are affected (ssh, remote desktop...) all other traffic (web surfing,...) will be transparently rerouted through the VPN.
Which login should I use to connect to the new VPN system?
You must use the login of your SLAC window account, and this account should be enabled for "dialup services".
When putting your login into Cisco anyconnect client's interface do not prefix it with "SLAC\", only put your login name in the field.