Temporary failure resolving 'httpredir.debian.org'

In trying to update/upgrade UNIHIKER, I receive the following output in my terminal window:

root@unihiker:~# sudo apt update
Err:1 http://httpredir.debian.org/debian buster InRelease
 Temporary failure resolving 'httpredir.debian.org'
Err:2 http://security.debian.org buster/updates InRelease
 Temporary failure resolving 'security.debian.org'
Err:3 http://httpredir.debian.org/debian buster-updates InRelease
 Temporary failure resolving 'httpredir.debian.org'
Err:4 http://httpredir.debian.org/debian buster-backports InRelease
 Temporary failure resolving 'httpredir.debian.org'
Reading package lists... Done
Building dependency tree       
Reading state information... Done
164 packages can be upgraded. Run 'apt list --upgradable' to see them.
W: Failed to fetch http://httpredir.debian.org/debian/dists/buster/InRelease  Temporary failure resolving 'httpredir.debian.org'
W: Failed to fetch http://httpredir.debian.org/debian/dists/buster-updates/InRelease  Temporary failure resolving 'httpredir.debian.org'
W: Failed to fetch http://httpredir.debian.org/debian/dists/buster-backports/InRelease  Temporary failure resolving 'httpredir.debian.org'
W: Failed to fetch http://security.debian.org/dists/buster/updates/InRelease  Temporary failure resolving 'security.debian.org'
W: Some index files failed to download. They have been ignored, or old ones used instead.
root@unihiker:~#

I understand the issue but I don't know how to fix it. Here is initial part of the ifconfig command output:

root@unihiker:~# ifconfig -a
br0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
       inet 10.1.2.3  netmask 255.255.255.0  broadcast 10.1.2.255
       inet6 fe80::2e0:4cff:fe9e:fec1  prefixlen 64  scopeid 0x20<link>
       ether 00:e0:4c:9e:fe:c1  txqueuelen 1000  (Ethernet)
       RX packets 10017  bytes 776921 (758.7 KiB)
       RX errors 0  dropped 0  overruns 0  frame 0
       TX packets 12591  bytes 8643775 (8.2 MiB)
       TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

My desktop that is connected to the UNIHIKER is successful with the following command:

$ ping httpredir.debian.org
PING debian.map.fastlydns.net (146.75.106.132) 56(84) bytes of data.
64 bytes from 146.75.106.132: icmp_seq=1 ttl=54 time=11.7 ms
64 bytes from 146.75.106.132: icmp_seq=2 ttl=54 time=11.3 ms
^C
 

How do I enable the bridge connection on the UNIHIKER to use the LAN Gateway? Thanks.

Regards.