I saw this suggested in another thread but that thread was locked so I'd like to propose this here. Having multiple IP addresses is one of the touted features of IPv6, but also of note is that due to

On-going Pre-release Firmware Trial for Omada Controllers ER7212PC V1 (Built-in Omada SDN Controller 6.0) Pre-release (Released on 22nd Jan, 2026) Closed Pre-release Firmware Trial for Omada Controlle

Please add a local DNS server, like dnsmasq, to the ER605. It's a bug for a business router that's running DHCP to not be able to resolve local host names.