diff --git a/.dev/config.toml b/.dev/config.toml
index 4c8032444..19e963d94 100644
--- a/.dev/config.toml
+++ b/.dev/config.toml
@@ -1,8 +1,8 @@
-httpPort = 4001
+httpPort = 44643
 noDaemon = true
 
 [client]
-url = "http://localhost:4001"
+url = "http://localhost:44643"
 
 [gui]
 port = 3001
diff --git a/doc/local-development.md b/doc/local-development.md
index 26bbb7014..122c1f5e1 100644
--- a/doc/local-development.md
+++ b/doc/local-development.md
@@ -14,13 +14,13 @@ cd path/to/exo
 exo run
 ```
 
-If all goes well, you should be able to manage your server and gui processes at [http://localhost:4000](http://localhost:4000). Please note that this is the _installed_ exo gui that you are viewing, not the development instance. The development instance runs on port `4001` and can be accessed at [http://localhost:4001](http://localhost:4001). The development mode GUI has a "DEV" indicator in the footer so that you can tell at a glance which instance you are using.
+If all goes well, you should be able to manage your server and gui processes at [http://localhost:43643](http://localhost:43643). Please note that this is the _installed_ exo gui that you are viewing, not the development instance. The development instance runs on port `44643` and can be accessed at [http://localhost:44643](http://localhost:44643). The development mode GUI has a "DEV" indicator in the footer so that you can tell at a glance which instance you are using.
 
 The `exo` CLI runs against the installed instance by default, but you can change to the development instance by adding the following to your exo config file (located at `~/.exo/config.toml`):
 
 ```
 [client]
-url = "http://localhost:4001"
+url = "http://localhost:44643"
 ```
 
 Now all `exo` commands will run against the development instance. To run against the installed instance again, remove or comment out these lines from your `config.toml`.
diff --git a/gui/.env.development b/gui/.env.development
index 1393130db..b5dd420e3 100644
--- a/gui/.env.development
+++ b/gui/.env.development
@@ -1 +1 @@
-VITE_API_PORT=4001
+VITE_API_PORT=44643
diff --git a/gui/.env.production b/gui/.env.production
index ba7171f9f..9f2e76101 100644
--- a/gui/.env.production
+++ b/gui/.env.production
@@ -1 +1,2 @@
-VITE_API_PORT=4000
+# FIXME: this should come from the config.toml
+VITE_API_PORT=43643
diff --git a/gui/vite.config.js b/gui/vite.config.js
index c9a5a2b77..83b017edb 100644
--- a/gui/vite.config.js
+++ b/gui/vite.config.js
@@ -2,8 +2,8 @@ import { defineConfig } from 'vite';
 import { svelte } from '@sveltejs/vite-plugin-svelte';
 
 // Vite server runs on 3001 in development, which is proxied from the
-// `exo` server running on 4001. In production, exo serves the GUI and
-// the API on port 4000.
+// `exo` server running on 44643. In production, exo serves the GUI and
+// the API on port 43643.
 const port = 3001;
 
 // https://vitejs.dev/config/
diff --git a/internal/config/config.go b/internal/config/config.go
index 3692b56b3..739f39d52 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -111,12 +111,12 @@ func setDefaults(cfg *Config) {
 	}
 
 	if cfg.HTTPPort == 0 {
-		cfg.HTTPPort = 4000
+		cfg.HTTPPort = 43643
 	}
 
 	// Log
 	if cfg.Log.SyslogPort == 0 {
-		cfg.Log.SyslogPort = 4500
+		cfg.Log.SyslogPort = 43550
 	}
 
 	// GUI
diff --git a/internal/config/defaultconfig.toml b/internal/config/defaultconfig.toml
index 37e1d9a01..120fabe45 100644
--- a/internal/config/defaultconfig.toml
+++ b/internal/config/defaultconfig.toml
@@ -12,7 +12,7 @@
 # runDir = "/path/to/exo-home/run"
 
 # Port the daemon service listens on.
-# httpPort = 4000
+# httpPort = 43643
 
 ## Logging subsystem that collects logs from running services.
 [log]
diff --git a/internal/exod/main.go b/internal/exod/main.go
index cfcca4118..778afe728 100644
--- a/internal/exod/main.go
+++ b/internal/exod/main.go
@@ -211,6 +211,21 @@ func RunServer(ctx context.Context, flags map[string]string) {
 		Next:  mux,
 	})
 
+	go func() {
+		// Add a redirect to the new port number if a request is received on the old
+		// one. Ignore any error as that's most likely some other service attempting
+		// to listen on the same port. This is to allow people to upgrade seamlessly
+		// but we should be able to remove it soon after the next release. (Written
+		// on the 19th of Oct 2021)
+		http.ListenAndServe(":4000", http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
+			uri := *req.URL
+			uri.Host = fmt.Sprintf("localhost:%d", cfg.HTTPPort)
+			redirectTo := uri.String()
+			http.Redirect(resp, req, redirectTo, http.StatusMovedPermanently)
+			return
+		}))
+	}()
+
 	addr := cmdutil.GetAddr(cfg)
 	logger.Infof("listening for API calls at %s", addr)
 	cmdutil.ListenAndServe(ctx, &http.Server{