Cannot satisfy dependencies / kernel is not compatible

You will get the message “Cannot satisfy the following dependencies for...” or “The installed version of package kernel is not compatible, require...”

1. if the kernel version installed on your device does not match the kernel version required by the package you want to install. This happens very easily when you are using a snapshot image or a self-compiled image.
2. if you are using a snapshot image, and the snapshot packages are missing in current builds.
   • Solution: Wait some days, then check if the packages are being built again.

• Solution #1: Install all needed packages directly after installing the snapshot image, not on the next day.
• Solution #2: Try to install via opkg with option --force-depends (=Install/remove despite failed dependencies). Mind that this is likely to fail for kernel related packages (kmods). Note that failing/incompatible kernel modules may cause the device to crash or not to reboot properly.
• Solution #3: Make local copy of snapshot packages (not recommended, needs much space!)
• Solution #4: Use persistent kmods for snapshots for 3 months since the snapshot build:
  

  # Enable kmods repository
  . /etc/os-release
  KERNEL="$(opkg list-installed kernel)"
  cat << EOF >> /etc/opkg/distfeeds.conf
  src/gz openwrt_kmods http://downloads.openwrt.org/\
  snapshots/targets/${OPENWRT_BOARD}/kmods/${KERNEL##* }
  EOF

As general advice, especially for inexperienced users: Go for the latest stable release (if available for your device), not a snapshot version, then the package repositories will match and packages will be available.

• Solution #5: Do not install packages after flashing, but include them in your image.
• Solution #6: Compile the packages you want to install after flashing as modules. They will be built, but not included in the image.