A Tali-less playthru of ME3 is just plain terrible. If it were anyone else, other than Tali or Garrus, that died in that mission I'd say let it ride, but those 2 are just so damn important to that game.
I get the same site connection problems and need to refresh to fix it. I should note that these site connection problems are kinda random and don't always happen. More often than not I will connect to the site just fine, but every now and then I will get hit with it. I can't really predict it.