Hi,
new installations of NS8 use the “tls-alpn-01” which means that port 443 needs to be open or when in LAN it needs to be forwarded from the firewall.
To check the challenge that’s used:
api-cli run module/traefik1/get-acme-server
To set for example http-01 challenge to use port 80:
api-cli run module/traefik1/set-acme-server --data '{"challenge":"HTTP-01","url":"https://acme-v02.api.letsencrypt.org/directory"}'
See also Release notes — NS8 documentation
You must not install the apps on NS8, it should be a fresh NS8 installation before migration.
The migration tool migrates the apps. (like for example Nextcloud)
As regards onlyoffice, there’s no migration yet so you just can install it on the NS8 after the migration.