Oh, there’s (an attempt to have) a mDNS service on Turris by default… all the more reason to avoid using .local in DNS protocol as well. I know know little about mDNS, so I can’t really help you with turris.local.
The router’s local IP tends to be fixed, so you can add a static record manually (say, turris.lan). There are threads for that here, e.g. Cannot resolve hostname turris itself