I bought a 24 port managed switch, it is a cool thing to have in your private network, since they are basically given away for free nowadays when serious people move from 1 gigabit to 10 gigabit. I don’t foresee my network going 10G in the near future so an enterprise grade 1G switch almost for free seems like a good deal.
I bought one on Swiss Tutti (“Blocket” for Swedish people, “Avito” for Russians) for 20 bucks and it arrived a few days later (I am still waiting to get deceived on Tutti or Ricardo even though there are scammers on these platforms too). Since I did not get to know the correct IP address of the switch (the seller told me the wrong one but I do not count this as deceived, he tried to help) I could not connect to the web management interface and used the managed switch as a dumb switch for a while. I even bought a serial to usb cable until simply doing the reasonable thing…
The reasonable thing, at least afaik, is to connect an ethernet cable between the switch and the a computer with a NIC, start Wireshark or whatever similar tool you have at hand (tcpdump for you cli aficionados), and take a look. When restarting the switch one of the first packets clearly discloses the IP address of the device (I forgot to make a screenshot but it is obvious when you inspect), and then you can manually set your computer to have an IP address in the same subnetwork, get to the web ui and change the IP address of the switch. If you actually have one of those ancient Linksys router like myself, you better take advantage of the compatibility mode in IE since they apparently put some trainee on coding the web ui and it does not load in a modern browser…
Voila, hopefully this saved some people waiting for serial to usb cables from Guangdong via aliexpress et al.