How to get a different mirror in zypper - one machine choice is broken and cannot update

I have several Opensuse 15.1 machines - my two oldest (upgraded from 41.0 41.1 41.2 15.0 then 15.1) cannot update due to opensuse.ucom.am error - all others work fine (they were 15.0 upgraded to 15.1)
How to I change what mirror zypper selects to download from?

# zypper ref ; zypper -n up
Repository 'Packman 15.1 Repository' is up to date.                             
Repository 'adobe' is up to date.                                               
Repository 'openSUSE-Leap-15.1-Non-Oss' is up to date.                          
Repository 'openSUSE-Leap-15.1-Oss' is up to date.                              
Repository 'openSUSE-Leap-15.1-Update' is up to date.                           
Repository 'TeamViewer - x86_64' is up to date.                                 
All repositories have been refreshed.
Loading repository data...
Reading installed packages...

The following 2 packages are going to be upgraded:
  yast2-installation yast2-storage-ng

2 packages to upgrade.
Overall download size: 675.6 KiB. Already cached: 0 B. After the operation,
additional 11.7 KiB will be used.
Continue? [y/n/v/...? shows all options] (y): y
Retrieving package yast2-storage-ng-4.1.90-lp151.2.9.1.x86_64
                                           (1/2), 439.2 KiB (  2.0 MiB unpacked)
Retrieving delta: ./x86_64/yast2-storage-ng-4.1.85_4.1.90-lp151.2.6.1_lp151.2.9.1.x86_64.drpm, 130.5 KiB
Retrieving: yast2-storage-ng-4.1.85_4.1.90-lp151.2.6.1_lp151.2.[error (394 B/s)]
Download (curl) error for 'https://download.opensuse.org/update/leap/15.1/oss/x86_64/yast2-storage-ng-4.1.85_4.1.90-lp151.2.6.1_lp151.2.9.1.x86_64.drpm':
Error code:  Unsupported protocol or redirect (Location: http://opensuse.ucom.am/update/leap/15.1/oss/x86_64/yast2-storage-ng-4.1.85_4.1.90-lp151.2.6.1_lp151.2.9.1.x86_64.drpm)
Error message: Redirect to protocol "http" not supported or disabled in libcurl

Abort, retry, ignore? [a/r/i/...? shows all options] (a): a
ABORT request: Aborting requested by user
History:
 - Can't provide ./x86_64/yast2-storage-ng-4.1.85_4.1.90-lp151.2.6.1_lp151.2.9.1.x86_64.drpm

Retrieving: yast2-storage-ng-4.1.90-lp151.2.9.1.x86_64.rpm ..............[error]
Download (curl) error for 'https://download.opensuse.org/update/leap/15.1/oss/x86_64/yast2-storage-ng-4.1.90-lp151.2.9.1.x86_64.rpm':
Error code:  Unsupported protocol or redirect (Location: http://opensuse.ucom.am/update/leap/15.1/oss/x86_64/yast2-storage-ng-4.1.90-lp151.2.9.1.x86_64.rpm)
Error message: Redirect to protocol "http" not supported or disabled in libcurl

Abort, retry, ignore? [a/r/i/...? shows all options] (a): a
Problem occurred during or after installation or removal of packages:
Installation has been aborted as directed.
Please see the above error message for a hint.

Hi
Perhaps re-configure zypper configuration on the system temporarily to not use the delta rpms?

the site http://opensuse.ucom.am got fixed 2.5 hours after my attempts to update my systems.

I still would like to know where the mirror site gets chosen in zypper and how to force it to select another.

I have 20 virtual opensuse 15.1 machines and 4 had this issue. I know how to do this with Redhat yum. There has to be a way with zypper or it needs an enhancement to bypass broken mirror sites.

Hi
It doesn’t, it’s a function of mirrorbrain…
https://en.opensuse.org/MirrorBrain

Also there are infrastructure issues at present, so that maybe the issue your striking… https://status.opensuse.org/

With that many systems look at using something like RMT (while SUSE centric it is available and works with openSUSE) to make a local copy to deploy?

It has nothing to do with mirror. Reconfigure your repositories to use plain HTTP instead of HTTPS.