Friends, sorry, most probably it is described somewhere but due to common search words I’m confused while trying to find it (and don’t see anything relevant in chirpstack.toml, neither in UI settings)
Does chirpstack v4 support external join-server, and does it support single or any number of them simultaneously?
If you search this page for ‘join’, you’ll find the section:
https://www.chirpstack.io/docs/chirpstack/configuration.html
I have not used that functionality under v4 and cannot speak to it, though.
I’m using this configuration to interact with the Semtech Join Server (LoRa Cloud):
Example:
[[join_server.servers]]
join_eui="ffffffbb00000000"
server="https://js.loracloud.com:7009/api/v1/rens/rens-XXX/lbi"
ca_cert="..."
tls_cert="..."
tls_key="..."
[[join_server.servers]]
join_eui="0016c001fffe0001"
server="https://js.loracloud.com:7009/api/v1/rens/rens-XXX/lbi"
ca_cert="..."
tls_cert="..."
tls_key="..."
Friends, thanks a lot for clarifications, it feels much better now 
I’ve seen the page but seemingly was confused whether it allows several join-servers configuration or not (though now it looks obvious)…