I noticed sometime when I upgrade the system it will changes the mirror automatically. I can see it move from my home country Indonesia to Japan or China server and it’s with default settings.
Update:
When I open /etc/yum.repos.d/fedora-updates.repo
file on [updates]
part there a line of:
metalink=https://mirrors.fedoraproject.org/metalink?repo=updates-released-f$releasever&arch=$basearch
I change the link to check the available mirror to my machine and open it from browser:
# Open on browser
https://mirrors.fedoraproject.org/metalink?repo=updates-released-f35&arch=x86_64
then I get the metalink
file that contain list of mirror available for my system:
...
<resources maxconnections="1">
<url protocol="rsync" type="rsync" location="ID" preference="100">rsync://fedora.mirror.angkasa.id/fedora-enchilada/linux/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="http" type="http" location="ID" preference="100">http://fedora.mirror.angkasa.id/pub/fedora/linux/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="http" type="http" location="JP" preference="99">http://ftp.riken.jp/Linux/fedora/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="rsync" type="rsync" location="JP" preference="99">rsync://ftp.riken.jp/fedora/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="https" type="https" location="JP" preference="99">https://ftp.riken.jp/Linux/fedora/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="http" type="http" location="JP" preference="98">http://ftp.jaist.ac.jp/pub/Linux/Fedora/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="rsync" type="rsync" location="JP" preference="98">rsync://ftp.jaist.ac.jp/pub/Linux/Fedora/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="http" type="http" location="TH" preference="97">http://mirror2.totbb.net/fedora/linux/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="rsync" type="rsync" location="TH" preference="97">rsync://mirror2.totbb.net/fedora/linux/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="https" type="https" location="CN" preference="96">https://mirrors.tuna.tsinghua.edu.cn/fedora/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="http" type="http" location="CN" preference="96">http://mirrors.tuna.tsinghua.edu.cn/fedora/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="rsync" type="rsync" location="CN" preference="96">rsync://mirrors.tuna.tsinghua.edu.cn/fedora/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="https" type="https" location="JP" preference="95">https://ftp.yz.yamagata-u.ac.jp/pub/linux/fedora-projects/fedora/linux/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="http" type="http" location="JP" preference="95">http://ftp.yz.yamagata-u.ac.jp/pub/linux/fedora-projects/fedora/linux/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="rsync" type="rsync" location="JP" preference="95">rsync://ftp.yz.yamagata-u.ac.jp/pub/linux/fedora-projects/fedora/linux/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="http" type="http" location="JP" preference="94">http://ftp.iij.ad.jp/pub/linux/Fedora/fedora/linux/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="rsync" type="rsync" location="JP" preference="94">rsync://ftp.iij.ad.jp/pub/linux/Fedora/fedora/linux/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="https" type="https" location="SG" preference="93">https://download.nus.edu.sg/mirror/fedora/linux/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="http" type="http" location="SG" preference="93">http://download.nus.edu.sg/mirror/fedora/linux/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="rsync" type="rsync" location="SG" preference="93">rsync://download.nus.edu.sg/fedora/linux/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="rsync" type="rsync" location="CN" preference="92">rsync://mirrors.bfsu.edu.cn/fedora/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="http" type="http" location="CN" preference="92">http://mirrors.bfsu.edu.cn/fedora/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="rsync" type="rsync" location="CN" preference="91">rsync://mirror.sjtu.edu.cn/fedora/linux/updates/35/Everything/x86_64/repodata/repomd.xml</url>
<url protocol="https" type="https" location="CN" preference="91">https://mirror.sjtu.edu.cn/fedora/linux/updates/35/Everything/x86_64/repodata/repomd.xml</url>
</resources>
...
May be you want to try it too then check for each servers (they are all mostly volunteering) why they not responding.
Update:
I tried to ping SERVER_ADDRESS -n4
for IP4 then ping SERVER_ADDRESS -n6
for IP6, and found it only works with IP4.
I check further from free web services to check IPv6:
I guess my country living in the past since it’s not able to use IPv6. 
You could also check with online available service to ping the server if it support IPv6 or not.
For example bellow are ping to Google:
And bellow ping to nearest server to me and look like they have not support for IPv6:

But it’s ok. The angkasa.id owner look like a good gentleman since he hosted lot of Linux Distros mirror update.
Another update:
Since from other post look like you have server that able to connect to IPv6, may be if you have extra spaces and bandwidths, you could also volunteering to host Fedora Linux update with IPv6. That would be awesome.