tried to update a RetroPie today, lots of issues reaching mirrors.gigenet.com. I mitigated it once by rebooting the RetroPie after it crashed & burned in the middle of doing a large update. All this did was trigger a new DNS lookup for my mirror. Eventually, it wandered back to the broken mirror. we fixed this.

 pi@mnretrogamer014:~ $ git clone https://github.com/hiulit/RetroPie-Convert-Videos.git
Cloning into 'RetroPie-Convert-Videos'...
remote: Enumerating objects: 154, done.
remote: Counting objects: 100% (154/154), done.
remote: Compressing objects: 100% (102/102), done.
remote: Total 461 (delta 92), reused 111 (delta 51), pack-reused 307
Receiving objects: 100% (461/461), 138.75 KiB | 2.31 MiB/s, done.
Resolving deltas: 100% (280/280), done.
pi@mnretrogamer014:~ $ cd RetroPie-Convert-Videos/
pi@mnretrogamer014:~/RetroPie-Convert-Videos $ sudo chmod +x retropie-convert-videos.sh
pi@mnretrogamer014:~/RetroPie-Convert-Videos $ ./retropie-convert-videos.sh --to-ces "yuv420p" --scraper "sselph" --convert-all
dpkg-query: no packages found matching ffmpeg

WHOOPS! The 'ffmpeg' package is not installed!

Would you like to install it now?
1) Yes
2) No
#? 1
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libmicrodns0 rpi-eeprom-images
Use 'sudo apt autoremove' to remove them.
The following additional packages will be installed:
  libavresample4
Suggested packages:
  ffmpeg-doc
The following NEW packages will be installed:
  ffmpeg libavresample4
0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
Need to get 1,536 kB of archives.
After this operation, 2,241 kB of additional disk space will be used.
Do you want to continue? [Y/n]
Get:1 http://archive.raspberrypi.org/debian buster/main armhf libavresample4 armhf 7:4.1.6-1~deb10u1+rpt1 [104 kB]
Get:2 http://archive.raspberrypi.org/debian buster/main armhf ffmpeg armhf 7:4.1.6-1~deb10u1+rpt1 [1,432 kB]
Fetched 1,536 kB in 1s (1,188 kB/s)
Selecting previously unselected package libavresample4:armhf.
(Reading database ... 126647 files and directories currently installed.)
Preparing to unpack .../libavresample4_7%3a4.1.6-1~deb10u1+rpt1_armhf.deb ...
Unpacking libavresample4:armhf (7:4.1.6-1~deb10u1+rpt1) ...
Selecting previously unselected package ffmpeg.
Preparing to unpack .../ffmpeg_7%3a4.1.6-1~deb10u1+rpt1_armhf.deb ...
Unpacking ffmpeg (7:4.1.6-1~deb10u1+rpt1) ...
Setting up libavresample4:armhf (7:4.1.6-1~deb10u1+rpt1) ...
Setting up ffmpeg (7:4.1.6-1~deb10u1+rpt1) ...
Processing triggers for man-db (2.8.5-2) ...
Processing triggers for libc-bin (2.28-10+rpi1) ...

/home/pi/RetroPie-Convert-Videos/utils/base.sh: line 105: /home/pi/RetroPie-Convert-Videos/logs/2020-09-12-11:11:11.log: No such file or directory
YIPPEE! The 'ffmpeg' package installation was successful!
dpkg-query: no packages found matching bc

WHOOPS! The 'bc' package is not installed!

Would you like to install it now?
1) Yes
2) No
#? 1
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libmicrodns0 rpi-eeprom-images
Use 'sudo apt autoremove' to remove them.
The following NEW packages will be installed:
  bc
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 101 kB of archives.
After this operation, 220 kB of additional disk space will be used.
0% [Connecting to mirrors.gigenet.com (69.65.16.171)]^C
pi@mnretrogamer014:~/RetroPie-Convert-Videos $ sudo apt install bc
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libmicrodns0 rpi-eeprom-images
Use 'sudo apt autoremove' to remove them.
The following NEW packages will be installed:
  bc
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 101 kB of archives.
After this operation, 220 kB of additional disk space will be used.
0% [Connecting to mirrors.gigenet.com (69.65.16.171)]^C
pi@mnretrogamer014:~/RetroPie-Convert-Videos $ sudo apt install bc
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libmicrodns0 rpi-eeprom-images
Use 'sudo apt autoremove' to remove them.
The following NEW packages will be installed:
  bc
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 101 kB of archives.
After this operation, 220 kB of additional disk space will be used.
0% [Waiting for headers]^C
pi@mnretrogamer014:~/RetroPie-Convert-Videos $ sudo apt install bc
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libmicrodns0 rpi-eeprom-images
Use 'sudo apt autoremove' to remove them.
The following NEW packages will be installed:
  bc
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 101 kB of archives.
After this operation, 220 kB of additional disk space will be used.
0% [Connecting to mirrors.gigenet.com (69.65.16.171)]^C