I reinstalled Turris OS 5.0.0. and get for luci-proto-relay:
root@turris:~# opkg install luci-proto-relay
Installing luci-proto-relay (git-20.016.50399-e1df28d-1.0) to root...
Downloading https://repo.turris.cz/hbs/omnia/packages/luci/luci-proto-relay_git-20.016.50399-e1df28d-1_all.ipk
Collected errors:
* check_data_file_clashes: Package luci-proto-relay wants to install file /usr/lib/lua/luci/model/network/proto_relay.lua
But that file is already provided by package * luci-compat
* opkg_install_cmd: Cannot install package luci-proto-relay.
And even though it seems to be “installed”, it is not listed under the interfaces. And if I move the above file and install the package it does still not show up under interfaces that can be added.