Technically speaking, a mesh (i.e. “many-to-many”) layout is more resilient than a hub-and-spoke model where one device is the “master”, and increases the odds that any given file will be replicated to at least one other node.
It’s the downside to a many-to-many setup. As the number of nodes increases, managing them becomes more of a chore. Syncthing’s introducer feature might help. Some users have also used Syncthing’s REST API to help automate things.
As far as the other devices being in a disconnected state…
Are all of the devices on the same local network or are they in remote locations?
Are mobile connections involved?
Screenshots of Syncthing’s web GUI – with the relevant device panels expanded to show the connection details – would be helpful. Otherwise there’s going to be a lot of back and forth, sprinkled with a lot of guessing in between.
If the devices are running Windows, the Windows firewall needs to be set to “private” network instead of “public”, otherwise you’ll need to specifically add firewall rules to allow Syncthing be reachable by other nodes.
It is probably better and safer to create more server connections depending on which computers you have powered on. You may not have all five powered on at the same time and you may not want to necessarily have the master powered on all the time.
If you’re certain that the master is going to be up 100 percent of the time then that is different.
As an example I have three computers that are not all powered on at the same time and I back up my photos on my cell phone to my computers and I have a connection to each of the three computers and my cell phone so that I can power on any one of the three and synchronize my photos to that device.
Any two computers that I power on will synchronize photos with each other.