Hi @BlackWolf,
I think there may be a confusion between hostname and domain in the YunoHost context. Let me try to clarify.
How YunoHost handles domains and hostnames
When YunoHost asks you for a domain during postinstall, it expects a domain name like mydomain.local → not a full hostname.domain.tld structure. It’s also known that YunoHost modifies the system’s hostname based on the main domain you choose during postinstall (ref: GitHub issue #2065). This is why your hostname changed after setting up mydomain.local.
The .local TLD and mDNS
Domains ending in .local are fully supported since YunoHost v4.3. They use the mDNS protocol instead of standard DNS, meaning they are published automatically but only on your local network.
An important limitation: mDNS does not support subdomains :
So mydomain.local works, but yunohost.mydomain.local is not possible.
Also, if your existing network already relies on mydomain.local being resolved through standard DNS (e.g. by your router or a local DNS server), having YunoHost also publish mydomain.local via mDNS could create a naming conflict → which may explain why things break on your network. (Note: this is my hypothesis based on how mDNS works, not something explicitly documented by YunoHost.)
How to solve this
Option A – Use a fake TLD like .test
The official YunoHost documentation for VMs suggests using a dummy domain like yolo.test when you don’t have a real domain:
you can set up a dummy domain such as yolo.test and tweak your local /etc/hosts file such that this dummy domain points to the appropriate IP
So you could reinstall with mydomain.test (or any name you like), then add a line in the /etc/hosts file of each client machine:
192.168.x.x mydomain.test
Or, if your router supports custom DNS entries, configure it there so all devices resolve it automatically.
This way, your existing mydomain.local network stays untouched.
Option B – Keep .local but with a unique name
If you prefer the mDNS auto-discovery convenience, just pick a .local name that doesn’t conflict with anything on your network → for example myserver.local. YunoHost will also always publish yunohost.local by default.
Option C – Use a free YunoHost subdomain
YunoHost offers free domains under .nohost.me, .noho.st, or .ynh.fr with automatic DNS configuration. This avoids any local conflict entirely.
In short
The key takeaway: use a different domain name for YunoHost than the one your local network already uses. Option A (.test TLD + /etc/hosts) is probably the cleanest for a local VM setup.
Hope this helps! 