Ubiquity tries to connect to ubuntu repositories during install. Because the local network does not permit internet access from any MAC address [DHCP via MAC address identification], wubi installer winds up being served a local router html page, with no access to the repositories. Wubi then probably tries to read said router html page as repository page, and outputs the error.
I have attached the error logs extracted as per @bcbc's instructions, thanks! :)
After some research, present bug [#825704] appears to be caused by some wubi-flavored variant of bug [#346386] - https:/ /bugs.launchpad .net/ubuntu/ +source/ apt/+bug/ 346386.
Ubiquity tries to connect to ubuntu repositories during install. Because the local network does not permit internet access from any MAC address [DHCP via MAC address identification], wubi installer winds up being served a local router html page, with no access to the repositories. Wubi then probably tries to read said router html page as repository page, and outputs the error.
I have attached the error logs extracted as per @bcbc's instructions, thanks! :)