Setting the netmask default value to 255.255.255.0, when one goes into the network config to change from DHCP to static, would make much more sense to me.
I locked myself out (saved it thanks to cloud connectivity) of a new setup because I never thought I would have to change the netmask.
255.255.255.0 is a common default value.
255.255.255.255 is not a common default value.
I vote for this issue as it is a very low effort having also high impact. I expect this to literally be a change of one line in the textfield placeholder message, maybe I am wrong*Edit at the end.
In any case, changing this to a sane default that will avoid getting people to have to either interact with the HA terminal, use Cloud, or even re-install just because of not setting the NetMask is a no brainer in my perspective.
You only have to skip checking this field carefully once in order to lose access to the HA instance without automatic recovery possibility. It is never expected as the default behaviour of a Network config to have a /32 ( 255.255.255.255 ) mask and still interact with anything else inside the network - I cannot understand why this default was set like this. At least a warning event on Save - particularly for the Netmask Value being too limited - would be proper.
As an extra mile suggestion, HA should in general get any currently assigned NetMask ( from pre-existing DHCP assignment ) value on this interface and warn the user if it differs from the one in the input NetMask textfield.
Edit :
After checking the codebase for this, it is clear that the initial intention was to have the NetMask calculated automatically from the interface address field : frontend/src/data/hassio/network.ts at c4fcbf0613e2fbc537824cd27ba2358a1da2d4ef Ā· home-assistant/frontend Ā· GitHub called from frontend/src/panels/config/network/supervisor-network.ts at c4fcbf0613e2fbc537824cd27ba2358a1da2d4ef Ā· home-assistant/frontend Ā· GitHub
This means that the code is currently expecting to get a value from the interface Address field of something like 192.168.0.2/24 and not 192.168.0.2 as displayed now, the second one will be automatically calculated as a cidr of 1 host, aka Mask 255.255.255.255 from the code linked above and that is why we see it as ādefaultā value when we open the fieldsā¦
This is clearly a logic bug though, as the NetMask textfield is pretty much there for the same reason as this helper functionā¦ In short there is an inherent mechanism that will set the Mask textfield value, but it is not serving the intented purpose of displaying the current network NetMask, it only calculates that a single IP will be defined as a /32, which is only usefull on maybe firewall configuration, but certainly not on a networking one.
Based on the current flow, to me, the least wrong option is to not deduct the NetMask on the static input options ( start with an empty NetMask field ), or set the default to a safe /24 leaving the resposibility to the User for the rest ( as if the User went there, they are particularly trying to define these things by themselves ), plus an extra warning on NetMask size if smaller than 256 hosts as a final sanity check.