在我将LANtrace应用于带外连接后。我发现PySerial不传输8位，停止位1，因此协商总是失败，因为路由器总是只期望一个字节。在使用PuTTY跟踪连接后，我看到了两者之间的连接。在我更改代码以发送仅1个字母，延迟0.1秒后，协商成功。

#!/usr/bin/env python3
import serial
import time
import datetime

def connect_to_router(log_file):
    print("Connecting to router...")
    synchro = False
    # Open serial connection
    ser = serial.Serial(port='/dev/ttyUSB0', baudrate=57600, bytesize=8, parity="N", stopbits=1, timeout=3, rtscts=True)
    
    
    # Wait for login prompt
    while True:
        output = ser.readline().decode('utf-8', errors='replace').strip()
        
        if output != '':
            print(output)
            log_file.write(f"[{datetime.datetime.now()}] {output}\n")
        if 'Bit/s' in output:
            print("Synchronisation is Ok...")
            synchro = True
        elif not 'Bit/s' in output and synchro==False:
            print("Typing Return...")
            time.sleep(0.1)
            ser.write(b'\r')
        if 'Username:' in output:
            print("Typing Username...")
            time.sleep(0.1)
            ser.write('u'.encode('utf-8'))
            time.sleep(0.1)
            ser.write('s'.encode('utf-8'))
            time.sleep(0.1)
            ser.write('e'.encode('utf-8'))
            time.sleep(0.1)
            ser.write('r'.encode('utf-8'))
            time.sleep(0.1)
            ser.write(b'\r')
        if 'Password:' in output:
            print("Typing Passwort...")
            time.sleep(0.1)
            ser.write('T'.encode('utf-8'))
            time.sleep(0.1)
            ser.write('e'.encode('utf-8'))
            time.sleep(0.1)
            ser.write('s'.encode('utf-8'))
            time.sleep(0.1)
            ser.write('t'.encode('utf-8'))
            time.sleep(0.1)
            ser.write(b'\r')
        if 'Goodbye' in output:
            print("Logged out...")
            time.sleep(0.1)
            ser.write(b'\r')
            synchro = False
        if 'root@' in output:
            print("Typing Command...")
            time.sleep(0.1)
            ser.write('s'.encode('utf-8'))
            time.sleep(0.1)
            ser.write('h'.encode('utf-8'))
            time.sleep(0.1)
            ser.write('o'.encode('utf-8'))
            time.sleep(0.1)
            ser.write('w'.encode('utf-8'))
            time.sleep(0.1)
            ser.write(' '.encode('utf-8'))
            time.sleep(0.1)
            ser.write('m'.encode('utf-8'))
            time.sleep(0.1)
            ser.write('e'.encode('utf-8'))
            time.sleep(0.1)
            ser.write('m'.encode('utf-8'))
            time.sleep(0.1)
            ser.write(b'\r')
            
            break
        print("loop")
    return ser

def main():
    while True:
        try:
            # Open log file with timestamp in filename
            timestamp = datetime.datetime.now().strftime("%Y-%m-%d_%H-%M-%S")
            log_file = open(f"/home/wlanpi/log_{timestamp}.txt", "w")

            ser = connect_to_router(log_file)
            print("Logged in by this point...")
            # Read and log all remaining output from router
            while True:
                output = ser.readline().decode('utf-8', errors='replace').strip()
                if output != '':
                    print(output)
                    log_file.write(f"[{datetime.datetime.now()}] {output}\n")

                # Check if still logged in
                if 'Bit/s' in output:
                    print("Logged out, attempting to log back in...")
                    ser = connect_to_router(log_file)

        except (KeyboardInterrupt, serial.SerialException) as e:
            # User pressed CTRL-C or serial connection error occurred
            print(f"Exception: User pressed CTRL-C or serial connection error occurred{e}")
            ser = None  
            break

        finally:
            # Close serial connection and log file
            if ser is not None:
                ser.close()
            log_file.close()

if __name__ == '__main__':
    main()

这不是最好的答案，但至少现在有效。