When using syncthing I have found how to add shares to Syncthing and it is by using the add storage button in Syncthing config. Here is a screenshot after I have added a couple of shares.
So I just realized when I added the last share that after I filled in the new storage form and hit enter it fills in the form incorrectly. The internal and external parms are backwards.
@Stevek which version are you running with this? There recently was a fix released with 5.0.15 for the incorrect summary page but that was resolved). If you’re on an “older” version then this might already be addressed. If not, then this might be an additional instance where that was not fixed.