Some mobile network providers charge more for a tethering plan. They detect a desktop User Agent and block the network request. The request desktop site works by re-downloading the site 'pretending' to be desktop Firefox. Your mobile provider detects this change and blocks access to the site.

Unfortunately there is nothing Mozilla can do about your mobile provider's network polices. You can try contacting them and see if they will remove the block.

thanks for the excellent reply. CSpire just ignored my question. dolphin browser lets me select the user agent and I can use the desktop user agent to view the non-mobile versions of pages. it seems our brilliant Mozilla community could do the same.

See also https://addons.mozilla.org/mobile/addon/phony/

You may be hitting the same issue as https://bugzilla.mozilla.org/show_bug.cgi?id=810690.

If so, a possible workaround would be the following: 1) Choose "Request Desktop Site" (which brings you to CSpire's page) 2) Click back to return to the page you were on 3) Reload the page