Here are some more details. Swiping from left after navigation does not really open the new page's SideDrawer. This gesture actually navigates back to Page1. Now, for some reason Page1 is not restored correctly, so the SideDrawer appears empty. This is easily worked around -- move the code that sets DrawerContent in OnAppearing method, but first set it to null:
protected override void OnAppearing()
Drawer.DrawerContent = null;
Drawer.DrawerContent = App.ConnectService.Menu;
With this change the app would work like this: on swipe from left, the app navigates back to Page1 with the SideDrawer already open and populated. Using navigation with SideDrawer in each page is not supported in Xamarin.Forms. The problem is in the NavigationController, which gets the gesture, hence SideDrawer of Page2 and Page3 is never open. Setting navigation controller's InteractivePopGestureRecognizer.Enabled
disallows the swipe altogether. The same problem is discussed and solved in Xamarin.iOS in the following article:
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