Code:
root@et10000:~# opkg install enigma2-plugin-systemplugins-serviceapp
Installing enigma2-plugin-systemplugins-serviceapp (1+git161+02956ea) on root.
Downloading http://188.165.252.42/feeds/satdreamgr-6/et10000/enigma2-plugin-systemplugins-serviceapp_1+git161+02956ea-r20
190827_et10000.ipk.
wget: server returned error: HTTP/1.1 404 Not Found
Collected errors:
 * opkg_download_backend: Failed to download http://188.165.252.42/feeds/satdreamgr-6/et10000/enigma2-plugin-systemplugin
s-serviceapp_1+git161+02956ea-r20190827_et10000.ipk, wget returned 1.
 * opkg_install_pkg: Failed to download enigma2-plugin-systemplugins-serviceapp. Perhaps you need to run 'opkg update'?
 * opkg_solver_install: Cannot install package enigma2-plugin-systemplugins-serviceapp.

root@et10000:~# opkg update
Downloading http://188.165.252.42/feeds/satdreamgr-6/all/Packages.gz.
Updated source 'satdreamgr-all'.
Downloading http://188.165.252.42/feeds/satdreamgr-6/et10000/Packages.gz.
Updated source 'satdreamgr-et10000'.
Downloading http://188.165.252.42/feeds/satdreamgr-6/mips32el/Packages.gz.
Updated source 'satdreamgr-mips32el'.
Downloading http://188.165.252.42/feeds/picons/Packages.gz.
Updated source 'picons'.
Downloading http://188.165.252.42/feeds/satdreamgr-extra-et10000/Packages.gz.
Updated source 'satdreamgr-extra-et10000'.
Downloading http://188.165.252.42/feeds/satdreamgr-extra/Packages.gz.
Updated source 'satdreamgr-extra'.
Downloading http://188.165.252.42/feeds/satdreamgr-extra-mips32el/Packages.gz.
Updated source 'satdreamgr-extra-mips32el'.

root@et10000:~# opkg install enigma2-plugin-systemplugins-serviceapp
Installing enigma2-plugin-systemplugins-serviceapp (1+git161+02956ea) on root.
Downloading http://188.165.252.42/feeds/satdreamgr-6/et10000/enigma2-plugin-systemplugins-serviceapp_1+git161+02956ea-r20
190827_et10000.ipk.
wget: server returned error: HTTP/1.1 404 Not Found
Collected errors:
 * opkg_download_backend: Failed to download http://188.165.252.42/feeds/satdreamgr-6/et10000/enigma2-plugin-systemplugin
s-serviceapp_1+git161+02956ea-r20190827_et10000.ipk, wget returned 1.
 * opkg_install_pkg: Failed to download enigma2-plugin-systemplugins-serviceapp. Perhaps you need to run 'opkg update'?
 * opkg_solver_install: Cannot install package enigma2-plugin-systemplugins-serviceapp.
root@et10000:~#
Same error on servicemp3 package too