router: TP-Link Archer C59 v2
OpenWrt device page: https://openwrt.org/toh/tp-link/tp-link_archer_c59
I had OpenWrt and luci GUI installed fine, but encountered a problem so I reset the firmware (using the reset button on the router). Afterwards, I could not connect to luci GUI ("page cannot be displayed), so I used PuTTY (SSH) to log in and issue commands "opkg update" and "opkg install luci" but get error "cannot install package luci".
I then performed sysupgrade to 19.07.1 firmware listed on the OpenWrt product page (see above) and tried again to install luci, but still getting same error.
Collected errors: * opkg_download: Failed to download http://downloads.openwrt.org/snapshots/targets/ar71xx/generic/kmods/4.14.125-1-4798db7ce04dcb4337e44dbaa2a958a0/Packages.gz, wget returned 8. Collected errors: * satisfy_dependencies_for: Cannot satisfy the following dependencies for luci: * libiwinfo20200105 * opkg_install_cmd: Cannot install package luci.