Nextcloud not reachable - disk space problem?

Since a few weeks I cannot reach my Nextcloud instance
I tried to reinstall (snap)
and set back a backup of installation and files

However it does not work
I got multiple errors but none of them seemed to get to sollution
Now I wonder if there is a simple reason such as unsufficient space

My specifications from the server:

Ubuntu 20.04.1 LTS (GNU/Linux 5.4.0-56-generic x86_64)

System information as of di 1 dec 2020 16:59:40 CET

  System load:              0.09
  Usage of /:               5.8% of 3.58TB
  Memory usage:             6%
  Swap usage:               0%
  Temperature:              37.0 C
  Processes:                212
  Users logged in:          0
  IPv4 address for docker0: 
  IPv4 address for eno1:    
  IPv6 address for eno1:    

0 updates can be installed immediately.
0 of these updates are security updates.

root@server1:/# root@server1:/# df -h
bash: root@server1:/#: No such file or directory
root@server1:/# Filesystem      Size  Used Avail Use% Mounted on
tmpfs           7,8G     0  7,8G   0% /dev/shm
tmpfs           5,0M     0  5,0M   0% /run/lock
tmpfs           7,8G     0  7,8G   0% /sys/fs/cgroup
/dev/sdb1       511M  7,8M  504M   2% /boot/efi
/dev/loop2       56M   56M     0 100% /snap/core18/1885
/dev/loop1       98M   98M     0 100% /snap/core/10126
/dev/loop3      126M  126M     0 100% /snap/docker/471
/dev/loop4       56M   56M     0 100% /snap/core18/1932
/dev/loop0       98M   98M     0 100% /snap/core/10185
/dev/loop5       68M   68M     0 100% /snap/lxd/18150
/dev/loop6      9,2M  9,2M     0 100% /snap/canonical-livepatch/94
/dev/loop7      9,2M  9,2M     0 100% /snap/canonical-livepatch/95
/dev/loop8      4,3M  4,3M     0 100% /snap/tree/18
/dev/loop11     126M  126M     0 100% /snap/docker/461
/dev/loop10      71M   71M     0 100% /snap/lxd/16922
/dev/loop9      253M  253M     0 100% /snap/nextcloud/23743
tmpfs           1,6G     0  1,6G   0% /run/user/1000

Is there any sollution in this problem?