No it’s not about my browser - it’s the yum that fails to get metadata for RHEL7 repo (and ONLY for it) after a successful registration. All repos setup in my Katello are successfully synced, have errata. If disable this problematic RHEL7 repo in yum (config or cmdline) - I can install packages from any other Katello manged repos without any issues.
root@host:~/bin # subscription-manager list
+-------------------------------------------+
    Installed Product Status
+-------------------------------------------+
Product Name:   Red Hat Software Collections (for RHEL Server)
Product ID:     201
Version:        3
Arch:           x86_64
Status:         Subscribed
Status Details:
Starts:         07/11/2017
Ends:           07/10/2018
Product Name:   Red Hat Enterprise Linux Server
Product ID:     69
Version:        7.4
Arch:           x86_64
Status:         Subscribed
Status Details:
Starts:         07/11/2017
Ends:           07/10/2018
root@host:~/bin # subscription-manager status
+-------------------------------------------+
   System Status Details
+-------------------------------------------+
Overall Status: Current
root@host:~/bin # yum repolist
Loaded plugins: enabled_repos_upload, package_upload, product-id, search-disabled-repos, subscription-manager, tracer_upload
https://host/pulp/repos/ORGANIZATION/PROD/PROD_INFRA_RHEL7_SERVER/content/dist/rhel/server/7/7Server/x86_64/os/repodata/repomd.xml: [Errno 14] HTTPS Error 404 - Not Found
Trying other mirror.
To address this issue please refer to the below knowledge base article
https://access.redhat.com/articles/1320623
If above article doesn't help to resolve this issue please open a ticket with Red Hat Support.
https://host/pulp/repos/ORGANIZATION/PROD/PROD_INFRA_RHEL7_SERVER/content/dist/rhel/server/7/7Server/x86_64/os/repodata/repomd.xml: [Errno 14] HTTPS Error 404 - Not Found
Trying other mirror.
repo id                                           repo name                                                                status
centos-sclo-rh/x86_64                             CentOS-7 - SCLo rh                                                        6,853
centos-sclo-sclo/x86_64                           CentOS-7 - SCLo sclo                                                        510
epel/x86_64                                       Extra Packages for Enterprise Linux 7 - x86_64                           12,439
foreman/x86_64                                    Foreman 1.17                                                                453
foreman-plugins/x86_64                            Foreman plugins 1.17                                                        253
group_theforeman-tfm-ror51/x86_64                 Copr repo for tfm-ror51 owned by @theforeman                                325
katello/x86_64                                    Katello 3.6                                                                  33
katello-candlepin/x86_64                          Candlepin: an open source entitlement management system.                      3
katello-client/x86_64                             Katello Client 3.6                                                           17
pulp/7Server/x86_64                               Pulp Community Release                                                       59
puppetlabs-deps/x86_64                            Puppet Labs Dependencies El 7 - x86_64                                       17
puppetlabs-pc1/x86_64                             Puppet Labs PC1 Repository el 7 - x86_64                                    138
puppetlabs-products/x86_64                        Puppet Labs Products El 7 - x86_64                                          225
rhel-7-server-rpms/7Server/x86_64                 Red Hat Enterprise Linux 7 Server (RPMs)                                      0
sensu/7Server/x86_64                              sensu                                                                       103
repolist: 21,428
Uploading Enabled Reposistories Report
Loaded plugins: product-id, subscription-manager