Having problems with Thread and ToString

Hi everyone!

Im working on a personal project that started as a console program, now i wanted to port the code to unity and it doesnt want to cooporate unfortunatly.

So a controller in unity shall update objects with data from a server

The class that communicates with the server looks something like this. Readwrite runs on a separate thread thats starts when the controller calls for the "server class"

 private void readWrite()
 {
       /*Runs a for loop to gain access to data, sends commands via write, and then reads the network stream*/
 }

 public void write(string message)
 {
     /***Works****/
 }

 public string read()
 {
     byte[] data = new byte[1024];
     StringBuilder recieved = new StringBuilder();

     int numberOfBytesRead = 0;

     // Incoming message may be larger than the buffer size, therefore reads all available data through this loop before stitching it togheter. 
     do
     {
         numberOfBytesRead = networkStream.Read(data, 0, data.Length);
         recieved.AppendFormat("{0}", Encoding.ASCII.GetString(data, 0, numberOfBytesRead));
     }
     while (networkStream.DataAvailable);
     
     
     return recieved.ToString(); // <---- This gives the exception "ToString can only be called from the main thread. Constructors and field initializers will be executed from the loading thread when loading a scene."
 }

As you can see the the read does not work, and throws an exception talking about ToString must be on the main thread. I cant really figure out how to solve this so any help would be very appriciated. Thank you beforehand!