Maybe you're still eyeing this thread months later. If you're wanting to understand Lain, I would say to just be careful not to get too lost in the technology. That's the mistake that I personally feel a lot of people make when they try to understand Lain because they want it to be a prediction about the internet. In reality, I believe that there is actually a lot about being human and being lonely in terms of thematic material. It's kind of hard to just spill out my own interpretation because I think this is a very complex piece of work. What do you think is happening yourself? We could discuss that and build off of each other's experiences. I personally tend to take a lot of the "symbols" you might see as literal happenings in order to explain the plot.
I would recommend you to, if you're really interested, rewatch having understood the basic plot and use what you know to piece together the "what's going on" (I'd say pay special attention to Layer 9, what Eiri and the Knights say about their ideology, Lain's origin, and Layers 12 and 13) . Then you'll be able to pick apart the "lore" of the world, which can help you to understand the "what were the creators saying" later. Some supplements you can use for this include various interviews with the creators that can be found in the query
>>729 suggested, and the Lain Playstation game. It isn't really a game, but a collection of files that are meant to help you understand Lain as a character in a completely different timeline from the anime, so to speak. There's no hard translation, and buying a copy will cost you a couple hundred, but there is an English translation of everything in a pdf that you can find at
http://psx.lain.pl/, and the site
http://laingame.net/about.html recreates the game structure online with all the original video clips.
