diff --git a/assets/js/components/Config/DeviceModal/Modbus.vue b/assets/js/components/Config/DeviceModal/Modbus.vue
index 1568972aa..acf3fb724 100644
--- a/assets/js/components/Config/DeviceModal/Modbus.vue
+++ b/assets/js/components/Config/DeviceModal/Modbus.vue
@@ -46,7 +46,7 @@
 			class="me-2"
 			required
 			:model-value="id || defaultId"
-			@input="$emit('update:id', $event.target.value)"
+			@update:model-value="(v) => $emit('update:id', v)"
 		/>
 	</FormRow>
 	<div v-if="connection === MODBUS_CONNECTION.TCPIP">
@@ -62,7 +62,7 @@
 				class="me-2"
 				required
 				:model-value="host"
-				@input="$emit('update:host', $event.target.value)"
+				@update:model-value="(v) => $emit('update:host', v)"
 			/>
 		</FormRow>
 		<FormRow :id="formId('modbusPort')" :label="$t('config.modbus.port')">
@@ -73,7 +73,7 @@
 				class="me-2 w-50"
 				required
 				:model-value="port || defaultPort"
-				@input="$emit('update:port', $event.target.value)"
+				@update:model-value="(v) => $emit('update:port', v)"
 			/>
 		</FormRow>
 		<FormRow
@@ -142,7 +142,7 @@
 				:choice="baudrateOptions"
 				required
 				:model-value="baudrate || defaultBaudrate"
-				@input="$emit('update:baudrate', parseInt($event.target.value))"
+				@update:model-value="(v) => $emit('update:baudrate', parseInt(v))"
 			/>
 		</FormRow>
 		<FormRow :id="formId('modbusComset')" :label="$t('config.modbus.comset')">
@@ -154,7 +154,7 @@
 				:choice="comsetOptions"
 				required
 				:model-value="comset || defaultComset"
-				@input="$emit('update:comset', $event.target.value)"
+				@update:model-value="(v) => $emit('update:comset', v)"
 			/>
 		</FormRow>
 	</div>
@@ -263,9 +263,9 @@ export default defineComponent({
 			this.setProtocolByCapabilities(newValue);
 			this.$emit("update:modbus", this.selectedModbus);
 		},
-		modbus(newValue: MODBUS_TYPE) {
+		modbus(newValue: MODBUS_TYPE, oldValue: MODBUS_TYPE) {
 			if (newValue) {
-				this.setConnectionAndProtocolByModbus(newValue);
+				this.setConnectionAndProtocolByModbus(newValue, oldValue);
 			}
 		},
 		connection(newValue: MODBUS_CONNECTION, oldValue: MODBUS_CONNECTION) {
@@ -298,8 +298,8 @@ export default defineComponent({
 				? MODBUS_PROTOCOL.TCP
 				: MODBUS_PROTOCOL.RTU;
 		},
-		setConnectionAndProtocolByModbus(modbus?: MODBUS_TYPE) {
-			switch (modbus) {
+		setConnectionAndProtocolByModbus(newModbus?: MODBUS_TYPE, oldModbus?: MODBUS_TYPE) {
+			switch (newModbus) {
 				case MODBUS_TYPE.RS485_SERIAL:
 					this.connection = MODBUS_CONNECTION.SERIAL;
 					this.protocol = MODBUS_PROTOCOL.RTU;
@@ -313,6 +313,11 @@ export default defineComponent({
 					this.protocol = MODBUS_PROTOCOL.TCP;
 					break;
 			}
+
+			// when switching from serial to TCP/IP, default protocol to Modbus-TCP (rtu=false)
+			if (oldModbus === MODBUS_TYPE.RS485_SERIAL && newModbus === MODBUS_TYPE.RS485_TCPIP) {
+				this.protocol = MODBUS_PROTOCOL.TCP;
+			}
 		},
 		formId(name: string): string {
 			return `${name}-${this.componentId}`;
diff --git a/assets/js/components/Config/ModbusProxyConnection.vue b/assets/js/components/Config/ModbusProxyConnection.vue
new file mode 100644
index 000000000..981aa6193
--- /dev/null
+++ b/assets/js/components/Config/ModbusProxyConnection.vue
@@ -0,0 +1,126 @@
+<template>
+	<Modbus
+		v-model:baudrate="localConnection.settings.baudrate"
+		v-model:comset="localConnection.settings.comset"
+		v-model:device="localConnection.settings.device"
+		:component-id="`proxy-${index}`"
+		:host="getHost(localConnection.settings.uri)"
+		:port="getPort(localConnection.settings.uri)"
+		:capabilities="['rs485', 'tcpip']"
+		hide-modbus-id
+		:default-baudrate="DEFAULT_BAUDRATE"
+		:default-comset="DEFAULT_COMSET"
+		:default-port="DEFAULT_PORT"
+		:modbus="initialModbusType"
+		@update:host="(host) => updateHost(host)"
+		@update:port="(port) => updatePort(port)"
+		@update:modbus="(modbus) => updateModbus(modbus)"
+	/>
+</template>
+
+<script lang="ts">
+import { defineComponent } from "vue";
+import Modbus from "./DeviceModal/Modbus.vue";
+import {
+	MODBUS_BAUDRATE,
+	MODBUS_COMSET,
+	MODBUS_TYPE,
+	type ModbusProxy,
+	type ModbusProxySettings,
+} from "@/types/evcc";
+import deepClone from "@/utils/deepClone";
+
+export const DEFAULT_BAUDRATE = MODBUS_BAUDRATE._9600;
+export const DEFAULT_COMSET = MODBUS_COMSET._8N1;
+export const DEFAULT_PORT = 502;
+
+function getModbusType(s: ModbusProxySettings) {
+	if (s.device) {
+		return MODBUS_TYPE.RS485_SERIAL;
+	}
+	return s.rtu ? MODBUS_TYPE.RS485_TCPIP : MODBUS_TYPE.TCPIP;
+}
+
+export default defineComponent({
+	name: "ModbusProxyConnection",
+	components: { Modbus },
+	props: {
+		connection: {
+			type: Object as () => ModbusProxy,
+			required: true,
+		},
+		index: {
+			type: Number,
+			required: true,
+		},
+	},
+	emits: ["update:connection"],
+	data() {
+		return {
+			DEFAULT_BAUDRATE,
+			DEFAULT_COMSET,
+			DEFAULT_PORT,
+			localConnection: deepClone(this.connection),
+			initialModbusType: getModbusType(this.connection.settings),
+		};
+	},
+	watch: {
+		localConnection: {
+			handler(newVal: ModbusProxy) {
+				if (newVal) {
+					this.$emit("update:connection", newVal);
+				}
+			},
+			deep: true,
+		},
+	},
+	methods: {
+		getHost(uri?: string) {
+			return uri?.split(":")[0] || "";
+		},
+		getPort(uri?: string) {
+			return uri?.split(":")[1] || "";
+		},
+		updateHost(newHost?: string) {
+			const port = this.getPort(this.localConnection.settings.uri);
+
+			if (port === "" && newHost === undefined) {
+				this.localConnection.settings.uri = undefined;
+			} else {
+				this.localConnection.settings.uri = `${newHost === undefined ? "" : newHost}:${port}`;
+			}
+		},
+		updatePort(newPort?: string) {
+			const host = this.getHost(this.localConnection.settings.uri);
+			if (host === "" && newPort === undefined) {
+				this.localConnection.settings.uri = undefined;
+			} else {
+				this.localConnection.settings.uri = `${host}:${newPort === undefined ? "" : newPort}`;
+			}
+		},
+		updateModbus(modbus: MODBUS_TYPE) {
+			this.initialModbusType = modbus;
+
+			switch (modbus) {
+				case MODBUS_TYPE.RS485_SERIAL:
+					this.localConnection.settings.uri = undefined;
+					this.localConnection.settings.rtu = undefined;
+					if (!this.localConnection.settings.baudrate) {
+						this.localConnection.settings.baudrate = DEFAULT_BAUDRATE;
+					}
+					if (!this.localConnection.settings.comset) {
+						this.localConnection.settings.comset = DEFAULT_COMSET;
+					}
+					break;
+				case MODBUS_TYPE.RS485_TCPIP:
+				case MODBUS_TYPE.TCPIP:
+					this.localConnection.settings.device = undefined;
+					this.localConnection.settings.baudrate = undefined;
+					this.localConnection.settings.comset = undefined;
+					this.localConnection.settings.rtu = modbus === MODBUS_TYPE.RS485_TCPIP;
+					break;
+			}
+		},
+	},
+});
+</script>
diff --git a/assets/js/components/Config/ModbusProxyModal.vue b/assets/js/components/Config/ModbusProxyModal.vue
index d1a051c8a..e0f7eb1d2 100644
--- a/assets/js/components/Config/ModbusProxyModal.vue
+++ b/assets/js/components/Config/ModbusProxyModal.vue
@@ -85,19 +85,12 @@
 										</div>
 									</h5>
 								</div>
-								<Modbus
-									v-model:baudrate="c.settings.baudrate"
-									v-model:comset="c.settings.comset"
-									v-model:device="c.settings.device"
-									:modbus="getModbus(c.settings)"
-									:component-id="`proxy-${index}`"
-									:host="getHost(c.settings.uri)"
-									:port="getPort(c.settings.uri)"
-									:capabilities="['rs485', 'tcpip']"
-									hide-modbus-id
-									@update:host="(host) => updateHost(host, c.settings)"
-									@update:port="(port) => updatePort(port, c.settings)"
-									@update:modbus="(modbus) => updateModbus(c.settings, modbus)"
+								<ModbusProxyConnection
+									:connection="c"
+									:index="index"
+									@update:connection="
+										(connection) => (values[index] = connection)
+									"
 								/>
 							</div>
 						</div>
@@ -143,17 +136,13 @@ import "@h2d2/shopicons/es/regular/arrowdown";
 import "@h2d2/shopicons/es/regular/plus";
 import "@h2d2/shopicons/es/regular/trash";
 import JsonModal from "./JsonModal.vue";
-import {
-	MODBUS_COMSET,
-	MODBUS_CONNECTION,
-	MODBUS_PROTOCOL,
-	MODBUS_PROXY_READONLY,
-	MODBUS_TYPE,
-	type ModbusProxy,
-	type ModbusProxySettings,
-} from "@/types/evcc";
+import { MODBUS_PROXY_READONLY, type ModbusProxy } from "@/types/evcc";
 import ASCII_DIAGRAM from "./modbus-diagram.txt?raw";
-import Modbus from "./DeviceModal/Modbus.vue";
+import ModbusProxyConnection, {
+	DEFAULT_BAUDRATE,
+	DEFAULT_COMSET,
+	DEFAULT_PORT,
+} from "./ModbusProxyConnection.vue";
 import PropertyField from "./PropertyField.vue";
 import FormRow from "./FormRow.vue";
 import SponsorTokenRequired from "./DeviceModal/SponsorTokenRequired.vue";
@@ -162,7 +151,14 @@ import { defineComponent } from "vue";
 
 export default defineComponent({
 	name: "ModbusProxyModal",
-	components: { JsonModal, Modbus, FormRow, PropertyField, SponsorTokenRequired, SelectGroup },
+	components: {
+		JsonModal,
+		ModbusProxyConnection,
+		FormRow,
+		PropertyField,
+		SponsorTokenRequired,
+		SelectGroup,
+	},
 	props: {
 		isSponsor: Boolean,
 	},
@@ -170,10 +166,6 @@ export default defineComponent({
 	data() {
 		return {
 			ASCII_DIAGRAM,
-			MODBUS_PROXY_READONLY,
-			MODBUS_CONNECTION,
-			MODBUS_PROTOCOL,
-			MODBUS_TYPE,
 		};
 	},
 	computed: {
@@ -188,12 +180,6 @@ export default defineComponent({
 		formId(index: number, name: string) {
 			return `modbusproxy-connection-${index}-${name}`;
 		},
-		getModbus(s: ModbusProxySettings) {
-			if (s.device) {
-				return MODBUS_TYPE.RS485_SERIAL;
-			}
-			return s.rtu ? MODBUS_TYPE.RS485_TCPIP : MODBUS_TYPE.TCPIP;
-		},
 		getReadonlyHelp(readonly = MODBUS_PROXY_READONLY.FALSE): string {
 			return this.$t(`config.modbusproxy.readonly.help.${readonly}`);
 		},
@@ -203,41 +189,12 @@ export default defineComponent({
 				port: highestPort + 1,
 				readonly: MODBUS_PROXY_READONLY.FALSE,
 				settings: {
-					uri: ":502",
-					baudrate: 9600,
-					comset: "8N1" as MODBUS_COMSET,
+					uri: `:${DEFAULT_PORT}`,
+					baudrate: DEFAULT_BAUDRATE,
+					comset: DEFAULT_COMSET,
 				},
 			});
 		},
-		getHost(uri?: string) {
-			return uri?.split(":")[0] || "";
-		},
-		getPort(uri?: string) {
-			return uri?.split(":")[1] || "";
-		},
-		updateHost(newHost: string, settings: ModbusProxySettings) {
-			const port = this.getPort(settings.uri);
-			settings.uri = `${newHost}:${port}`;
-		},
-		updatePort(newPort: string | number, settings: ModbusProxySettings) {
-			const host = this.getHost(settings.uri);
-			settings.uri = `${host}:${newPort}`;
-		},
-		updateModbus(settings: ModbusProxySettings, modbus: MODBUS_TYPE) {
-			switch (modbus) {
-				case MODBUS_TYPE.RS485_SERIAL:
-					settings.uri = undefined;
-					settings.rtu = undefined;
-					break;
-				case MODBUS_TYPE.RS485_TCPIP:
-				case MODBUS_TYPE.TCPIP:
-					settings.device = undefined;
-					settings.baudrate = undefined;
-					settings.comset = undefined;
-					settings.rtu = modbus === MODBUS_TYPE.RS485_TCPIP;
-					break;
-			}
-		},
 	},
 });
 </script>
diff --git a/tests/config-modbusproxy.spec.ts b/tests/config-modbusproxy.spec.ts
index 2762fc764..383074d3d 100644
--- a/tests/config-modbusproxy.spec.ts
+++ b/tests/config-modbusproxy.spec.ts
@@ -87,6 +87,35 @@ test.describe("modbusproxy", async () => {
     await expect(modal).not.toContainText("Connection #1");
   });
 
+  test("modbusproxy serial defaults", async ({ page }) => {
+    await start();
+    await page.goto("/#/config");
+
+    const modbusproxyCard = page.getByTestId("modbusproxy");
+    await modbusproxyCard.getByRole("button", { name: "edit" }).click();
+    const modal = page.getByTestId("modbusproxy-modal");
+    await expectModalVisible(modal);
+
+    await modal.getByRole("button", { name: "Add proxy connection" }).click();
+    const deviceBox = modal.getByTestId("device-box");
+
+    await expect(deviceBox.getByLabel("Network")).toBeChecked();
+    await expect(deviceBox.getByLabel("Port")).toHaveValue("502");
+
+    // switch to RS485
+    await deviceBox.getByText("RS485", { exact: true }).click();
+    await expect(deviceBox.getByLabel("Baud rate")).toHaveValue("9600");
+    await expect(deviceBox.getByLabel("ComSet")).toHaveValue("8N1");
+
+    await deviceBox.getByLabel("Baud rate").selectOption("19200");
+
+    // switch to Network and back: defaults restored
+    await deviceBox.getByText("Network").click();
+    await deviceBox.getByText("RS485", { exact: true }).click();
+    await expect(deviceBox.getByLabel("Baud rate")).toHaveValue("9600");
+    await expect(deviceBox.getByLabel("ComSet")).toHaveValue("8N1");
+  });
+
   test("modbusproxy via db (yaml to json migration)", async ({ page }) => {
     await start(undefined, CONFIG_MODBUSPROXY_MIGRATE);
     await page.goto("/#/config");