failed to build Schulstick on Debian GNU/Linux bullseye/sid x86_64

[freddii]

Del libmbim-glib4 1.24.4-0.1~bpo10+1 [185 kB]
Del libmbim-proxy 1.24.4-0.1~bpo10+1 [88.4 kB]
Reading package lists...
Building dependency tree...
Reading state information...
[2021-01-28 21:45:18] lb binary_manifest 
P: Begin creating manifest...
[2021-01-28 21:45:18] lb binary_package-lists 
P: Begin installing local package lists...
[2021-01-28 21:45:18] lb binary_linux-image 
P: Begin install linux-image...
[2021-01-28 21:45:19] lb binary_memtest 
[2021-01-28 21:45:19] lb binary_grub-legacy 
[2021-01-28 21:45:19] lb binary_grub-pc 
[2021-01-28 21:45:19] lb binary_loopback_cfg 
P: Begin installing loopback.cfg...
[2021-01-28 21:45:19] lb binary_syslinux 
P: Begin installing syslinux...
Reading package lists...
Building dependency tree...
Reading state information...
Suggested packages:
  xorriso
The following NEW packages will be installed:
  isolinux
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 108 kB of archives.
After this operation, 212 kB of additional disk space will be used.
Err:1 http://ftp.de.debian.org/debian buster/main amd64 isolinux all 3:6.04~git20190206.bf6db5b4+dfsg1-1
  Temporary failure resolving 'ftp.de.debian.org'
E: Failed to fetch http://ftp.de.debian.org/debian/pool/main/s/syslinux/isolinux_6.04~git20190206.bf6db5b4+dfsg1-1_all.deb  Temporary failure resolving 'ftp.de.debian.org'
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
P: Begin unmounting filesystems...
P: Saving caches...
Reading package lists...
Building dependency tree...
Reading state information...
[ ⚠️  ] FAILED
[ ℹ️  ] this took 1 hours 52 minutes and 30 seconds and the work of many

[freddii]

seams i had network problems...