我在MX Linux可以上網，而apt-get update指令能連線到 https://mirrors.ocf.berkeley.edu/ 。
然而，我用apt-get upgrade卻無法連線到 https://mirrors.ocf.berkeley.edu/ ！
請問，我該如何解決這問題？

# 我成功地 apt-get update，系統能連線到 https://mirrors.ocf.berkeley.edu/
sparc@Mini:~
$ sudo apt-get update -y
Hit:1 http://debian.csie.ntu.edu.tw/debian bookworm-updates InRelease
Hit:2 http://debian.csie.ntu.edu.tw/debian bookworm InRelease
Hit:3 http://security.debian.org/debian-security bookworm-security InRelease
Hit:4 https://brave-browser-apt-release.s3.brave.com stable InRelease
Hit:5 https://mirrors.ocf.berkeley.edu/mx-packages/mx/repo bookworm InRelease
Reading package lists... Done

# 但我apt-get upgrade後，系統就說 Failed to fetch https://mirrors.ocf.berkeley.edu/
# 系統還建議我用 --fix-missing
sparc@Mini:~
$ sudo apt-get upgrade -y
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Calculating upgrade... Done
The following packages have been kept back:
mx-system
The following packages will be upgraded:
mx-installer
1 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
Need to get 517 kB of archives.
After this operation, 13.3 kB of additional disk space will be used.
Err:1 https://mirrors.ocf.berkeley.edu/mx-packages/mx/repo bookworm/main amd64 mx-installer amd64 23.10.03mx23
404 Not Found [IP: 169.229.200.70 443]
E: Failed to fetch https://mirrors.ocf.berkeley.edu/mx...3mx23_amd64.deb 404 Not Found [IP: 169.229.200.70 443]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

# 我於是apt-get update -y --fix-missing
sparc@Mini:~
$ sudo apt-get update -y --fix-missing
Hit:1 http://debian.csie.ntu.edu.tw/debian bookworm-updates InRelease
Hit:2 http://security.debian.org/debian-security bookworm-security InRelease
Hit:3 http://debian.csie.ntu.edu.tw/debian bookworm InRelease
Hit:4 https://brave-browser-apt-release.s3.brave.com stable InRelease
Hit:5 https://mirrors.ocf.berkeley.edu/mx-packages/mx/repo bookworm InRelease
Reading package lists... Done

# 然而，即便如此，但我再次 apt-get upgrade後，系統仍舊說 Failed to fetch https://mirrors.ocf.berkeley.edu/
sparc@Mini:~
$ sudo apt-get upgrade -y
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Calculating upgrade... Done
The following packages have been kept back:
mx-system
The following packages will be upgraded:
mx-installer
1 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
Need to get 517 kB of archives.
After this operation, 13.3 kB of additional disk space will be used.
Err:1 https://mirrors.ocf.berkeley.edu/mx-packages/mx/repo bookworm/main amd64 mx-installer amd64 23.10.03mx23
404 Not Found [IP: 169.229.200.70 443]
E: Failed to fetch https://mirrors.ocf.berkeley.edu/mx...3mx23_amd64.deb 404 Not Found [IP: 169.229.200.70 443]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

PS:
我電腦規格如下：
Operating System: MX Linux 23
KDE Plasma Version: 5.27.5
KDE Frameworks Version: 5.103.0
Qt Version: 5.15.8
Kernel Version: 6.0.0-6mx-amd64 (64-bit)
Graphics Platform: X11
Processors: 12 × AMD Ryzen 5 3600 6-Core Processor
Memory: 31.3 GiB of RAM
Graphics Processor: AMD Radeon RX 570 Series
Manufacturer: ASUS