Local domains are slow or not working

When your local domains have a slow response time or don't work at all, this may indicate issues with the mDNS protocol, browser DNS cache, system DNS cache, or system permissions.

To resolve it, try the following:

Check LocalCan's network permissions

1. Open macOS System Settings
2. Go to Privacy & Security
3. Scroll down to Local Network
4. Make sure LocalCan has permission (toggle switch is turned on)

Check if the issue is browser-specific

Test your local domain in different browsers (Chrome, Firefox, Safari) to determine if the slowdown only happens on a specific browser. If so, clear the browser's DNS cache.

Clear browser's DNS cache

Example for Chrome:

1. Navigate to chrome://net-internals/#dns
2. Click Clear host cache
3. Navigate to chrome://net-internals/#sockets
4. Click Close idle sockets, and then click Flush socket pools.

Clear system DNS cache

Run these commands in terminal to clear the system DNS cache and restart mDNSResponder:

sudo dscacheutil -flushcache
sudo killall -HUP mDNSResponder
sudo killall mDNSResponderHelper

Restart LocalCan

Choose Quit from LocalCan menu bar icon, or press ⌘Q.

Restart WiFi (turn off and on)

Press WiFi icon in menu bar, and turn the toggle switch off and on.

Restart your router or switch to different WiFi network

Some routers have unreliable mDNS protocol support or don't support it at all.

Most domain issues can be resolved by checking permissions, clearing DNS caches, and restarting network services. If the problem continues, it might indicate a deeper network configuration issue that requires additional investigation.

Further debugging

Query DNS Service Discovery (DNS-SD) for a specific domain

By running this command, you will be able to see if your DNS settings can resolve the domain to an IP address.

dns-sd -Q myapp.local

Example output showing IP addresses for myapp.local:

13:20:50.732  ...STARTING...
Timestamp     A/R  Flags    IF  Name            Type   Class  Rdata
13:20:50.858  Add  3        14  myapp.local.    Addr   IN     192.168.1.20
13:20:50.858  Add  3        14  myapp.local.    Addr   IN     198.19.249.3
13:20:50.858  Add  2        14  myapp.local.    Addr   IN     192.168.97.0

Check if your DNS settings are set up to resolve .local domains

scutil --dns

Example output showing resolver #2 designated for resolving .local domains:

...
resolver #2
  domain   : local
  options  : mdns
  timeout  : 5
  flags    : Request A records
  reach    : 0x00000000 (Not Reachable)
  order    : 300000
...