I read this topic (Cannot connect Xiaomi Gateway (lumi.gateway.v3) to HA - #17 by hoedha) and think my gateway is faulty too, is anything else to try?
My output nmap:
PORT STATE SERVICE VERSION
4321/tcp closed rwhois
9898/tcp closed monkeycom
MAC Address: 7C:49:EB:1A:44:13 (Unknown)
Warning: OSScan results may be unreliable because we could not find at least 1 open and 1 closed port
Device type: specialized
Running: iRobot embedded
OS CPE: cpe:/h:irobot:roomba_980
OS details: iRobot Roomba 980 vacuum cleaner
Network Distance: 1 hop