Your opkg install uses "Sim2" feeds that are no more available.

Change / modify the opkg files in /etc/opkg to have the correct link to the actual feed repository, hoping it will work. As your image is originally using sim2 feeds.

New feeds address compatible should look like,

http://jam2.japhar.com/feeds/OpenPLi-4/pli/dm800sev2/all/Packages.gz.
http://jam2.japhar.com/feeds/OpenPLi-4/pli/dm800sev2/dm800sev2/Packages.gz.
http://jam2.japhar.com/feeds/OpenPLi-4/pli/dm800sev2/mips32el/Packages.gz.

Then do the plugin update

opkg update
opkg install enigma2-plugin-systemplugins-wirelesslan

And do as explained in the topic indicated above, http://www.ourdreambox.com/ubbthreads.php?ubb=showflat&Number=13485&page=1

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