nothing works, shits broken

config.py

@@ -1,38 +1,86 @@
 import json
 import printer
 
+config_filename = "server_config.json"
+
 
 class PrinterConfig:
-    editables = {"printer_address", "printer_port"}
-    required_params = {"printer_address"}
-
-    def __init__(self):
-        self.printer_address = None
-        self.printer_port = 9100
-        self.printer_profile = "RP-F10-80mm"
-        self.__printer = None
-
-    def save(self):
-        with open("config.json", "w", encoding="utf-8") as ofd:
-            json.dump(self.__dict__, ofd, ensure_ascii=False)
+    editables = {"address", "port"}
+    required_params = {"address"}
+    _address = None
+    _port = 9100
+    _profile = "RP-F10-80mm"
+    _printer = None
+    _dirty = True
 
     def load(self):
-        with open("config.json", "r", encoding="utf-8") as ifd:
-            self.__dict__ = json.load(ifd)
+        """Load printer configuration from config.json file."""
+        with open(config_filename, "r", encoding="utf-8") as ifd:
+            loaded_config = json.load(ifd)
+            for param_name in self.editables:
+                if param_name in loaded_config:
+                    setattr(self, param_name, loaded_config[param_name])
+
+    def save(self):
+        """Save current printer configuration to config.json file."""
+        with open(config_filename, "w", encoding="utf-8") as ofd:
+            json.dump(
+                {"address": self.address, "port": self.port, "profile": self.profile},
+                ofd,
+                ensure_ascii=False,
+            )
 
     @property
     def complete(self):
+        """Check if all required parameters are set.
+
+        Returns:
+            bool: True if all required parameters are set, False otherwise.
+        """
         for param in self.required_params:
             if getattr(self, param) is None:
                 return False
         return True
 
+    @property
+    def port(self):
+        return self._port
+
+    @port.setter
+    def port(self, new_value: int):
+        if not isinstance(new_value, int) or 0 > new_value < 65535:
+            new_value = 9100
+        self._port = new_value
+
+    @property
+    def address(self):
+        return self._address
+
+    @address.setter
+    def address(self, new_value: str):
+        if not isinstance(new_value, str):
+            new_value = ""
+        self._address = new_value
+
+    @property
+    def profile(self):
+        return self._profile
+
+    @profile.setter
+    def profile(self, new_value: str):
+        raise AttributeError("Printer profile is a fixed value. Check config.py.")
+
     @property
     def printer(self):
-        if self.__printer is None:
-            self.__printer = printer.Printer(
-                address=self.printer_address,
-                port=self.printer_port,
-                profile=self.printer_profile,
+        if self._printer is not None:
+            self._printer.printer.close()
+
+        if self._dirty or self.printer is None:
+            self._printer = printer.Printer(
+                address=self.address,
+                port=self.port,
+                profile=self.profile,
             )
-        return self.printer
+            self._dirty = False
+
+        return self._printer