We have all had that experience when the Cisco Anyconnect client immediately disconnects after you have logged on and then starts reconnecting again. Its not life threatening, just irritating. The issue appears to be caused by an MTU mismatch, but this can be tweaked on the ASA based on the profile. This post shows how to fix the problem at the ASA CLI.
The config needs to added to the default remote profile under the webvpn stanza, however we don’t like messing around with default policies so we will modify the custom group policy for our remote users.
group-policy REMOTE-POLICY internal group-policy REMOTE-POLICY attributes dns-server value x.x.x.x x.x.x.x vpn-tunnel-protocol ssl-client split-tunnel-policy tunnelall webvpn anyconnect mtu 1300
And that’s it!