I recently had to switch out my older router to the latest PlusNet “stock” router as it was playing up. The old one had a “guest” WiFi capability which I liked, and so I set about trying to add it to the new one.
I quite like this new router (“Technicolor TG582n FTTC”), especially given that it's effectively a freebie. It took a while for me to learn to navigate the PlusNet-branded web-based configuration, but I soon got most of my LAN setting back in.
And then it turns out there's a telnet CLI! To search for references, as there's little help, know that the router seems to be a Thomson make. I found a number of sites and CLI PDFs (e.g., TG787-SIP_CLI.pdf) with more or less information.
An excellent site to start with is this one. I used information on this site to add my static IP addresses (“dhcp server lease add ...”).
There's a dedicated page to adding extra SSIDs (you can have up to 5); I did have to follow that page's instructions on manually bridging the new SSID. There's mention on the Net about BT branded routers requiring SSID IDs 1 & 2 to be reserved, so search for that if you need to; I just added #1.
I shan't explain the commands, as the page above pretty much does that, but I will highlight what information is important (bold+underline is important output, underline is custom input [depending upon the output or your choices).
These added a working, open guest WiFi connection, isolated from my (secured) main network:
wireless mssid iflist wireless mssid ifadd ssid=your-guest-ssid-name-here -> Allocated ssid id[0/1] ethernet port[wl_ssid1_local0] wireless mssid ifconfig ssid_id=1 apisolation=enabled secmode=disable wireless mssid ifattach ssid_id=1 # wlan_1 = new name, unique to SSID eth bridge ifadd intf=wlan_1 dest=wl_ssid1_local0 logging=disabled eth bridge ifconfig intf=wlan_1 logging=disabled eth bridge ifattach intf=wlan_1 logging=disabled eth bridge iflist saveall