So I got a Hub4 to replace my Hub3 and have experienced strange issues. It's not quite a full disconnect just time outs and packet loss. I can ping 18.104.22.168 but the hub's management IP 192.168.0.1 stops responding and I have to reboot it, this happens every day. I also get weird DNS issues where I can't resolve simple stuff, DNS is using VM's own dns servers 22.214.171.124 and 126.96.36.199 and falls back to 188.8.131.52.
The Hub3 still works fine, I'm not returning that until the Hub4 is stable. I had issues with the Hub3 as well going from Hub2 so I know that given enough time "they" will eventually iron out (some of) the biggest issues however I haven't got time to wait for that since now I'm locked down and working from home......
Hub4 (modem mode) > Unifi USG Router WAN port> Unifi Switch >AP's and wired clients