I see that the link for this plugin is no longer active? Does anyone have a link where I can download it from, or maybe someone who has a copy and can send it to me? Thanks.

Here is the website, take a look:
http://gstools.de/

I found it, but the download link gives me a 404 error. I tried to register (in case you need to register to download it) but that didn't work as well.

Well, then I can't help you, as I've had a HDD crash some time ago and so I've lost 500 GB of data.

Greets

Thank you very much!

can you suggest a reason why the game might crash on that command? there is a client with id 2 and the string is previously defined. on every sendstring the game crashes. i use A8 engine. SendVar works fine.

Well this is not good. You create an empty string with the size of 0!
Do it like this:

I had actually done it like that... anyhow... for some reason it doesn't work (I use the code provided as an example in the help file for GSTNet and it still gives an error). I guess there's some incompatibility with newer versions of Game Studio or I don't know I guess I'll have to forget about an in-game chat for now. Funny thing is that when I run it in debug mode, it works fine, but then it gives me an error and crashes when I run it normally. Maybe there needs to be a wait command somewhere in between?

There is something wrong with the plugin, not the GS version. I cant use it too, with A6 Comm.
Instead, your best friend is the event function. Whenever you need to send text, use an event and send the text with it as a second parameter. I implemented login and chat system this way.

PS.: You should keep in mind that I just found the worst bug that could be found. I wrote to nfs42 about it and I am waiting for an answer.
Once you join a session and leave, you cannot rejoin successfuly. I managed to join, but the client doesnt load a level. After that I load a level manualy and create a player entity, but the current server entity doesnt get created. Synchronize doesnt do anything in this situation. Its like I'm not connected, but the server and client say "2 clients"...