I have spent hours, tried EVERYTHING suggested to fix the 1101, 1000, and 30 error codes when adding a new Sonos One SL speaker to my system. I have tried the solutions repeatedly, and nothing worked …. UNTIL - i went to my router settings; i checked the list of devices on my wi-fi and found the problem - the Sonos Roam that i had added months before was stuck on the list as a ‘paused’ device on a 2.4ghz frequency. I set it up using 5ghz and it worked fine; the problem was when i tried to add a new speaker (One SL) it would not update no matter what i did i could not register it - until i unpaused this old install remnant roam device that i didnt even know was listed on my network (all were unplugged, this was still there). 

When i unpaused the phantom device on my network and tried to register the new device for the millionth time again, it worked! I had powered on just the roam and one sl, all other speakers were unplugged; i had rebooted the network; i had unpaused the non-existant device from my router wi-fi device list; and it worked! 

may the odds be ever in your favor.