Prebuilt eSDK toolchains from download.yoctoproject.org take long time (~30 minutes) to install, as the install process tries to contact Hash Equivalence Server typhoon.yocto.io:8686 of the original builder multiple times and eventually times out.

$ ./poky-glibc-x86_64-core-image-minimal-aarch64-qemuarm64-toolchain-ext-3.1.8.sh 
Poky (Yocto Project Reference Distro) Extensible SDK installer version 3.1.8
============================================================================
Enter target directory for SDK (default: ~/poky_sdk): /OE/poky-sdk-3.1.8
You are about to install the SDK to "/OE/poky-sdk-3.1.8". Proceed [Y/n]? y
Extracting SDK..............done
Setting it up...
Extracting buildtools...
Preparing build system...
Parsing recipes: 100% |####################################################################################################################################| Time: 0:00:07
Initialising tasks: 100% |#################################################################################################################################| Time: 0:00:01
Loading cache: 100% |######################################################################################################################################| Time: 0:00:00
WARNING: Error contacting Hash Equivalence Server typhoon.yocto.io:8686: [Errno 110] Connection timed out                                                  | ETA:  0:00:00
WARNING: Error contacting Hash Equivalence Server typhoon.yocto.io:8686: [Errno 110] Connection timed out
WARNING: Error contacting Hash Equivalence Server typhoon.yocto.io:8686: [Errno 110] Connection timed out
Initialising tasks: 100% |#################################################################################################################################| Time: 0:26:12
done
SDK has been successfully set up and is ready to be used.
Each time you wish to use the SDK in a new shell session, you need to source the environment setup script e.g.
 $ . /OE/poky-sdk-3.1.8/environment-setup-aarch64-poky-linux