Steps To Reproduce

(1) fresh install a VM (proxmox) , 4GB VM
(2) use something like nextcloud.mysite.it as DNS name
(4) Get the LE certificate, install failtoban (almost everything else as default)
(5) choose to install OnlyOffice (integrated)

Expected Result

Working OnlyOffice (integrated)

Actual Result

(1)
Onlyoffice DOCS path (in GUI) is wrong, missing "/" before "index.php"

https://nextcloud.mysite.itindex.php/apps/documentserver_community/

instead of (maybe)
https://nextcloud.mysite.it/index.php/apps/documentserver_community/

(2) Onlyoffice does not work at all. Seems some kind of misconfiguration (?)
Clicking on "save" (here https://nextcloud.mysite.it/settings/admin/onlyoffice)

Errore durante il tentativo di connessione (Client error: `GET https://nextcloud.mysite.it/index.php/apps/documentserver_community/healthcheck` resulted in a `404 Not Found` response

Using the "demo version" of ONLYOFFICE docs everything works fine

Screenshots, Videos, or Pastebins

Additional Context

Tried reinstalling from scratch, same problem
I have another (older) virtually identical machine (only real difference, it's called archive.mysite.it and not nextcloud.mysite.it) that works fine (on another proxmox server), on a different version Nextcloud Hub 3 (25.0.5)

https://archivio.mysite.it/index.php/apps/documentserver_community/healthcheck
get a "true" (as it should be)

Instead on the brand-new 26.0.2
https://nextcloud.mysite.it/index.php/apps/documentserver_community/healthcheck
get a "page not found, go back to nextcloud)

Build Version

Nextcloud Hub 4 (26.0.2)

Environment

By downloading the VM

Environment Details

Proxmox-based VM
vzdump-qemu-999-2023_04_09-21_10_30.vma