Yet another slightly different Wi-Fi issue…

I am running a Journeyman x50. I just updated to 1.2.1 and everything seems fine and I don’t have any issues as described by others.
My controller is about 5 feet from the main house router and I have strong Wi-Fi connection to the controller as internet pages load fast and reliable.
However, when I try to connect with any of my computers to onefinity.local the web interface loads maybe 20% of the time.
I am on the same router connection, have tried it with and without VPN, rebooted all devices and so on. Also, this issue started with 1.1 firmware and continues with 1.2.1.
BTW, I tried all sorts of Ethernet connectors with my MacBook and no luck there either - same as other people described in the forum.
Any suggestions are most welcome.

I am going to make a few assumptions about your setup… Please correct me where I am wrong.
You have a single AP (Wi-Fi) device that all your computers use for connectivity.
I am going to guess that when you connect, via an Ethernet cable, your controller to some AP, Switch, or hub, on your network, all the other computers can connect to the 1F controller without issue, either by IP or as onefinity.local.
I am going to also guess that when you connect via Wi-Fi only, you see less consistent connectivity.

In many "wi-fi router’ devices, as a method to protect the ‘plug and play’ people, the wi-fi device is configured in such a way that different clients are not allowed to speak to one another. This is based on many people using things like default passwords, and setting the SSID to ‘visible’, etc. In order to mitigate someone from sitting outside your home, hopping on your wi-fi, and searching all the computers, the manufacturer tried to limit that connectivity.

If this is your case, you may see that wired devices can see wi-fi devices, and vice versa. In order to change this, and again, it depends on your router’s capabilities… I would first change the router password to something really obnoxious, long, and irritating; set the SSID broadcast to ‘off’ (note: this only stops the simpletons from seeing it, an scanner will still be able to find it, but those are people on a mission); set your SSID password, again, to something obnoxious (and if your wi-fi provides it, use the QR-Code); then disable the ‘client isolation’ or whatever it is called on your device; then see that all the things can see all the things. This may still be undesirable for you, depending on how your network is being used, for instance if you have kids and they share the QR code with their friends, etc.
Another consideration is the channel your AP is running on. If you are in a more populated area, there is plenty of cross channel interference. You can change the channel on your AP and reconnect your devices. This may eliminate some of the problems.
If you are running 2.4G things like microwaves can interfere as well. 5G increases speed, but limits distance, and walls / etc. drop it even faster. If there is a wall between, and there is electric wiring, or if you have steel stud construction, you are in a makeshift Faraday cage… so there are lots of things working against your wi-fi.
If you can wire directly into a hub or switch, that is going to get you the best possible connectivity.

Hope this helps. If I got it all wrong, that’s okay too. =)

Thanks Patrick for your detailed reply! Great advice indeed!
Your assumptions are quite correct and I will take your points and work through them. I’ll start with the channel setting as it seems the easiest solution.
Your help is appreciated.