I read somewhere that I have to set an ipv4 address, I'd prefer not to set a useless ipv4 address there.
I dont know if it is duckdns nor working properly, or my ISP's network. I can access davidshen84.duckdns.org from my home computer. But if I use my mobile phone network or a vpn, I cannot access that domain. I got connection reset error in the browser.
Traceroute Online - Tracert Tracks Full Path of IP Packet or Domain gives me this:
Start: 2025-08-03T04:43:03+0500
HOST: DNSChecker.org Loss% Snt Last Avg Best Wrst StDev
1.|-- ??? 100.0 3 0.0 0.0 0.0 0.0 0.0
2.|-- fd00:0:7::2b4 0.0% 3 0.5 0.9 0.5 1.3 0.4
3.|-- 2604:a880:ffff::1:a 0.0% 3 21.0 7.8 1.1 21.0 11.4
4.|-- 2a03:b0c0:fffd::a4 0.0% 3 0.4 0.6 0.4 0.8 0.2
5.|-- 2a03:b0c0:fffe::15c 0.0% 3 0.9 1.3 0.9 1.6 0.3
6.|-- 2a03:b0c0:fffe::113 0.0% 3 0.7 0.9 0.7 1.0 0.2
7.|-- ??? 100.0 3 0.0 0.0 0.0 0.0 0.0
8.|-- po3.chi-eqxch1-cr7.globalsecurelayer.com (2401:3cc0:10:50::1:44) 0.0% 3 20.2 20.3 20.2 20.5 0.2
9.|-- po20.lax-csla2-bb5.globalsecurelayer.com (2401:3cc0:10:50::1:4) 0.0% 3 65.9 66.1 65.9 66.3 0.2
10.|-- e1.syd-eqxsy5-bb1.globalsecurelayer.com (2401:3cc0:10:50::1:3) 0.0% 3 198.6 198.8 198.6 199.0 0.2
11.|-- po3.syd-eqxsy5-cr6.globalsecurelayer.com (2401:3cc0:10:50::1:180) 0.0% 3 198.5 198.7 198.5 198.9 0.2
12.|-- 2401:3cc0::4:45d 0.0% 3 198.6 198.8 198.6 198.8 0.1
13.|-- ndcs1-pe2-po3004.nsw.leaptel.network (2402:2c80:0:22f::66) 0.0% 3 199.0 199.0 199.0 199.0 0.0
14.|-- 2400-a844-0-1--56.nsw.leaptel.network (2400:a844:0:1::56) 0.0% 3 199.0 199.1 199.0 199.3 0.1
15.|-- 2400-a844-8000-5ba2-359b-e9eb-43b-5b58.nsw.leaptel.network (2400:a844:8000:5ba2: 0.0% 3 200.8 201.0 200.8 201.3 0.3
16.|-- 2400-a844-5bd5-0-c492-3bdb-58bf-f9a5.nsw.leaptel.network (2400:a844:5bd5:0:c492: 0.0% 3 209.8 209.3 208.5 209.8 0.6
17.|-- ??? 100.0 3 0.0 0.0 0.0 0.0 0.0
The 58bf:f9a5 node is my server's temporary GUA. So, maybe the problem is on in my networking setup?