A certain ufw rule doesn't work after reboot

I searched over the web and I could see related issues, still I couldn't figure out the root cause.

I am not familiar with iptables, but to secure a ubuntu 16.04 based computer which hosts a Jupyter Notebook server at port 5550, I tried to enable the firewall and allow my local IP only. Also, I allowed local any to port 22 for SSH, and 5800,5900 for RealVNC server.

They worked perfectly initially right after adding and reloading the firewall rules.

However, once I have restarted the computer (the host), the Jupyter server won't connect anymore. I then checked the SSH and the VNC, they are actually still working. Restarting the Jupyter notebook server won't help.

If I disable, then enable the ufw back, my Jupyter server can connect again. Appreciated if you can give me a hint.

Update: further testing, it actually works from WAN (allowing a range of WAN IP, they work after reboot), but not the LAN subnet mask 192.168.1.0/24.

Further update: I think I figured it out, it is about the WAN to WAN route-back. I can actually access locally if I use the server's local IP. I will stick to this for now.