Apex Local should always be reachable from a computer or other device on the same local network.
Make sure you use http: and not https:, as the Apex doesn't support encryption.
If the numerical IP address isn't working, you can try entering hostname.local, where hostname is the name of your apex from the network page. If you never renamed your system, default is apex.local.
Proxy won't be an issue in most home networks. Firewall could be, if you have aggressive anti-virus software.
Browsers can sometimes be temperamental about this as well. Try a different browser.
Or you can disable Apex DHCP and assign the Apex a static IP address which never changes, in the router software.