repo syncでエラー

なんか最近になってOP-TEE/QEMU環境をrepo syncしている途中で以下エラーが起こるようになってsyncが成功しなくなった＞＜。

$ repo sync -j3

... A new repo command ( 1.22) is available.
... You should upgrade soon:

    cp /home/andy/devel/optee/.repo/repo/repo /home/andy/bin/repo

Fetching project optee_linuxdriver.git
Fetching project optee_client.git
Fetching project qemu.git
Fetching projects:   9% (1/11)  Fetching project optee_os.git
Fetching projects:  18% (2/11)  Fetching project soc_term.git
Fetching projects:  27% (3/11)  Fetching project optee_test.git
Fetching projects:  36% (4/11)  Fetching project build.git
Fetching projects:  45% (5/11)  Fetching project bios_qemu_tz_arm.git
Fetching projects:  54% (6/11)  Fetching project linux.git
fatal: unable to access 'https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/': Failed to connect to git.kernel.org port 443: Network is unreachable
Fetching projects:  63% (7/11)  Fetching project busybox.git
Fetching projects:  72% (8/11)  Fetching project gen_rootfs.git
Fetching projects:  90% (10/11)  fatal: unable to access 'https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/': Failed to connect to git.kernel.org port 443: Network is unreachable
error: Cannot fetch linux.git

error: Exited sync due to fetch errorsfatal: unable to access 'https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/': Failed to connect to git.kernel.org port 443: Network is unreachable

のでググったら以下方法書いてあったのでためしたら治ったっぽい？
なんでうまく行ったのか不明だけどｗ−

sudo sysctl -w net.ipv4.tcp_window_scaling=0