3Com S7906E Command Reference Manual page 1837

By default, no redirect URL is defined.
Note that:
The redirect URL and the free IP must be in the same network segment; otherwise, the URL may
be inaccessible.
You can configure the dot1x url command for more than once but only the last one takes effect.
Related commands: display dot1x, dot1x free-ip.
Examples
# Configure the redirect URL as http://192.168.0.1.
<Sysname> system-view
[Sysname] dot1x url http://192.168.0.1
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