Ubuntu 20.04 no tcp4 ？

[hanfeicode]

sysctl -p
kernel.sysrq = 1
kernel.printk = 5
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

Ubuntu 20.04 LTS \n \l

lsof -i :5000
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
pproxy 7796 root 3u IPv6 65209 0t0 TCP *:5000 (LISTEN)