wireless: use sysfs, do not ping

frontend/ui/network/manager.lua

@@ -90,7 +90,7 @@ function NetworkMgr:beforeWifiAction(callback)
  end
 
 function NetworkMgr:isConnected()
-    if Device:isAndroid() then
+    if Device:isAndroid() or Device:isCervantes() then
         return self:isWifiOn()
     else
         -- `-c1` try only once; `-w2` wait 2 seconds
@@ -187,7 +187,7 @@ function NetworkMgr:getRestoreMenuTable()
     return {
         text = _("Automatically restore Wi-Fi connection after resume"),
         checked_func = function() return G_reader_settings:nilOrTrue("auto_restore_wifi") end,
-        enabled_func = function() return Device:isCervantes() or Device:isKobo() end,
+        enabled_func = function() return Device:isKobo() end,
         callback = function() G_reader_settings:flipNilOrTrue("auto_restore_wifi") end,
     }
 end