adb shell
settings put global tether_dun_required 0
restart device
My OS on high sierra didn't have the file needed so create it first. Otherwise just add the line
touch /etc/sysctl.conf
In sysctl.conf
net.inet.ip.ttl=65
I think restart is needed. Or, temporarily change TTL
sudo sysctl -w net.inet.ip.ttl=65