Description of problem:
After upgrade glib2 to 2.67.6-1.fc35 dnf and curl has connection error which happens randomly.

[mikhail@fedora ~]$ su -
Password: 
[root@fedora ~]# dnf upgrade --refresh
local repo                                      2.5 MB/s | 3.0 kB     00:00    
Fedora rawhide openh264 (From Cisco) - x86_64   1.4 kB/s | 989  B     00:00    
Fedora - Modular Rawhide - Developmental packag 8.9 kB/s | 5.0 kB     00:00    
Fedora - Modular Rawhide - Developmental packag 101 kB/s | 156 kB     00:01    
Fedora - Rawhide - Developmental packages for t  13 kB/s | 6.4 kB     00:00    
Dependencies resolved.
================================================================================
 Package        Architecture    Version                  Repository        Size
================================================================================
Upgrading:
 glib2          x86_64          2.67.6-1.fc35            rawhide          2.7 M

Transaction Summary
================================================================================
Upgrade  1 Package

Total download size: 2.7 M
Is this ok [y/N]: y
Downloading Packages:
glib2-2.67.6-1.fc35.x86_64.rpm                  1.3 MB/s | 2.7 MB     00:02    
--------------------------------------------------------------------------------
Total                                           1.0 MB/s | 2.7 MB     00:02     
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
  Preparing        :                                                        1/1 
  Upgrading        : glib2-2.67.6-1.fc35.x86_64                             1/2 
  Cleanup          : glib2-2.67.5-1.fc35.x86_64                             2/2 
  Running scriptlet: glib2-2.67.5-1.fc35.x86_64                             2/2 
  Verifying        : glib2-2.67.6-1.fc35.x86_64                             1/2 
  Verifying        : glib2-2.67.5-1.fc35.x86_64                             2/2 

Upgraded:
  glib2-2.67.6-1.fc35.x86_64                                                    

Complete!

================ Log Out / Log In ======================

[mikhail@fedora ~]$ su -
Password: 
[root@fedora ~]# dnf upgrade --refresh
local repo                                      3.0 MB/s | 3.0 kB     00:00    
Fedora rawhide openh264 (From Cisco) - x86_64   2.0 kB/s | 989  B     00:00    
Fedora - Modular Rawhide - Developmental packag 0.0  B/s |   0  B     00:00    
Errors during downloading metadata for repository 'rawhide-modular':
  - Curl error (7): Couldn't connect to server for https://mirrors.fedoraproject.org/metalink?repo=rawhide-modular&arch=x86_64 []
Error: Failed to download metadata for repo 'rawhide-modular': Cannot prepare internal mirrorlist: Curl error (7): Couldn't connect to server for https://mirrors.fedoraproject.org/metalink?repo=rawhide-modular&arch=x86_64 []
[root@fedora ~]# dnf upgrade --refresh
local repo                                      3.0 MB/s | 3.0 kB     00:00    
Fedora rawhide openh264 (From Cisco) - x86_64   0.0  B/s |   0  B     00:00    
Errors during downloading metadata for repository 'fedora-cisco-openh264':
  - Curl error (7): Couldn't connect to server for https://mirrors.fedoraproject.org/metalink?repo=fedora-cisco-openh264-rawhide&arch=x86_64 []
Error: Failed to download metadata for repo 'fedora-cisco-openh264': Cannot prepare internal mirrorlist: Curl error (7): Couldn't connect to server for https://mirrors.fedoraproject.org/metalink?repo=fedora-cisco-openh264-rawhide&arch=x86_64 []
Fedora - Modular Rawhide - Developmental packag 0.0  B/s |   0  B     00:00    
Errors during downloading metadata for repository 'rawhide-modular':
  - Curl error (7): Couldn't connect to server for https://mirrors.fedoraproject.org/metalink?repo=rawhide-modular&arch=x86_64 []
Error: Failed to download metadata for repo 'rawhide-modular': Cannot prepare internal mirrorlist: Curl error (7): Couldn't connect to server for https://mirrors.fedoraproject.org/metalink?repo=rawhide-modular&arch=x86_64 []
[root@fedora ~]# curl 'https://mirrors.fedoraproject.org/metalink?repo=rawhide-modular&arch=x86_64'
curl: (7) Couldn't connect to server
[root@fedora ~]# wget https://mirrors.fedoraproject.org/metalink?repo=rawhide-modular&arch=x86_64
[1] 4717
[root@fedora ~]# 
Redirecting output to ‘wget-log’.

[1]+  Exit 4                  wget https://mirrors.fedoraproject.org/metalink?repo=rawhide-modular
[root@fedora ~]# curl 'https://mirrors.fedoraproject.org/metalink?repo=rawhide-modular&arch=x86_64'
<?xml version="1.0" encoding="utf-8"?>
<metalink version="3.0" xmlns="http://www.metalinker.org/" type="dynamic" pubdate="Wed, 17 Mar 2021 21:56:00 GMT" generator="mirrormanager" xmlns:mm0="http://fedorahosted.org/mirrormanager">
 <files>
  <file name="repomd.xml">
   <mm0:timestamp>1615967282</mm0:timestamp>
   <size>6695</size>
   <verification>
    <hash type="md5">f7c36ad1f0c8958d7dff7ce9e49767fd</hash>
    <hash type="sha1">02b6b4f7f75bdb9c2d658f8bc258fa9baca85bc8</hash>
    <hash type="sha256">054eff57013a27c8ccc06c040fabc187a07ef2743ccdede62998a5b6b6f61c6b</hash>
    <hash type="sha512">e6229d99d9372f95deff4b1f87d1b6bf8c45baa354bdb4e34604eb80c1303816d916b45c644c5f107e41fcc8419af1a1dde5e6b4e77b7882685e4cefa5c9571b</hash>
   </verification>
   <mm0:alternates>
    <mm0:alternate>
      <mm0:timestamp>1615920204</mm0:timestamp>
      <size>6695</size>
      <verification>
       <hash type="md5">5f061af30ba2a71ffdf9be6005836774</hash>
       <hash type="sha1">be1c1c94673cc1bd0d987cf289f5d38b904ad628</hash>
       <hash type="sha256">c04ce1e91981e78f8fface1b31c5f5ecabecab5b31c5adccea72d09973c08a19</hash>
       <hash type="sha512">19f1bcf02f9e20919020950e155461b98a4cce11aad131d13afc837e62680e2e72bae9ca3c6e84bae67cd5808be76ee6a6598e2d7e193429e6dfa69d78c808f1</hash>
      </verification>
    </mm0:alternate>
    <mm0:alternate>
      <mm0:timestamp>1615794764</mm0:timestamp>
      <size>6695</size>
      <verification>
       <hash type="md5">8cf525bb3ddd718141566370fcb84fa2</hash>
       <hash type="sha1">8b99c96f9da29d5656f15b55dad75d66fc64e595</hash>
       <hash type="sha256">bbb0831bf32396a24f0acd54c466bbb72f6aaebd4a87498a8e47a1b4f52f4249</hash>
       <hash type="sha512">77b3921e414a3c04ffa5016f74d049649fab8982c86b00c565cfe2c3c15e51b5106284808dc845025ad3dd9728c457be9c5eb4caacad5f4d57c57f1e5c995571</hash>
      </verification>
    </mm0:alternate>
   </mm0:alternates>
   <resources maxconnections="1">
    <url protocol="https" type="https" location="GB" preference="100">https://www.mirrorservice.org/sites/dl.fedoraproject.org/pub/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="http" type="http" location="GB" preference="100">http://www.mirrorservice.org/sites/dl.fedoraproject.org/pub/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="rsync" type="rsync" location="GB" preference="100">rsync://rsync.mirrorservice.org/dl.fedoraproject.org/pub/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="rsync" type="rsync" location="DE" preference="99">rsync://fedora.tu-chemnitz.de/ftp/pub/linux/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="http" type="http" location="DE" preference="99">http://fedora.tu-chemnitz.de/pub/linux/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="http" type="http" location="DK" preference="98">http://mirrors.dotsrc.org/fedora-buffet/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="rsync" type="rsync" location="DK" preference="98">rsync://mirrors.dotsrc.org/fedora-buffet/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="https" type="https" location="DK" preference="98">https://mirrors.dotsrc.org/fedora-buffet/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="https" type="https" location="FR" preference="97">https://fr2.rpmfind.net/linux/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="http" type="http" location="FR" preference="97">http://fr2.rpmfind.net/linux/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="rsync" type="rsync" location="FR" preference="97">rsync://fr2.rpmfind.net/linux/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="http" type="http" location="FR" preference="96">http://mirrors.ircam.fr/pub/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="rsync" type="rsync" location="FR" preference="96">rsync://mirrors.ircam.fr/fedora-linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="rsync" type="rsync" location="FR" preference="95">rsync://distrib-coffee.ipsl.jussieu.fr/pub/linux/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="http" type="http" location="FR" preference="95">http://distrib-coffee.ipsl.jussieu.fr/pub/linux/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="http" type="http" location="GB" preference="94">http://mirror.bytemark.co.uk/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
    <url protocol="rsync" type="rsync" location="GB" preference="94">rsync://mirror.bytemark.co.uk/fedora/linux/development/rawhide/Modular/x86_64/os/repodata/repomd.xml</url>
   </resources>
  </file>
 </files>
</metalink>
[root@fedora ~]# dnf upgrade --refresh
local repo                                      3.0 MB/s | 3.0 kB     00:00    
Fedora rawhide openh264 (From Cisco) - x86_64   1.7 kB/s | 989  B     00:00    
Fedora - Modular Rawhide - Developmental packag  20 kB/s | 5.0 kB     00:00    
Fedora - Rawhide - Developmental packages for t  25 kB/s | 6.4 kB     00:00    
Dependencies resolved.
Nothing to do.
Complete!
[root@fedora ~]# dnf upgrade --refresh
local repo                                      3.0 MB/s | 3.0 kB     00:00    
Fedora rawhide openh264 (From Cisco) - x86_64   1.9 kB/s | 989  B     00:00    
Fedora - Modular Rawhide - Developmental packag  22 kB/s | 5.0 kB     00:00    
Fedora - Rawhide - Developmental packages for t  13 kB/s | 6.4 kB     00:00    
Dependencies resolved.
Nothing to do.
Complete!

================ Several minutes times later ======================

[root@fedora ~]# dnf upgrade --refresh
local repo                                                                                                                               3.0 MB/s | 3.0 kB     00:00    
Fedora rawhide openh264 (From Cisco) - x86_64                                                                                            1.8 kB/s | 989  B     00:00    
Fedora - Modular Rawhide - Developmental packages for the next Fedora release                                                            0.0  B/s |   0  B     00:00    
Errors during downloading metadata for repository 'rawhide-modular':
  - Curl error (7): Couldn't connect to server for https://mirrors.fedoraproject.org/metalink?repo=rawhide-modular&arch=x86_64 []
Error: Failed to download metadata for repo 'rawhide-modular': Cannot prepare internal mirrorlist: Curl error (7): Couldn't connect to server for https://mirrors.fedoraproject.org/metalink?repo=rawhide-modular&arch=x86_64 []
[root@fedora ~]# 



Before I observed this issue only in mock container
https://bugzilla.redhat.com/show_bug.cgi?id=1933506