Concerning my mounts, this is what mount shows:
root@OMV7-02:~# mount | column -t
192.168.178.19:/volume1/MEDIA on /srv/remotemount/SYN type nfs4 (rw,relatime,vers=4.0,rsize=8192,wsize=8192,namlen=255,hard,proto=tcp,timeo=14,retrans=2,sec=sys,clientaddr=192.168.178.12,local_lock=none,addr=192.168.178.19)
//192.168.178.19/MEDIA on /srv/remotemount/SYN_DS218j type cifs (rw,relatime,vers=3.0,cache=strict,username=johndoe,uid=0,noforceuid,gid=0,noforcegid,addr=192.168.178.19,file_mode=0755,dir_mode=0755,iocharset=utf8,soft,nounix,serverino,mapposix,reparse=nfs,rsize=4194304,wsize=4194304,bsize=1048576,retrans=1,echo_interval=60,actimeo=1,closetimeo=1)
//192.168.178.19/familie on /srv/remotemount/syn_fam type cifs (rw,relatime,vers=3.0,cache=strict,username=johndoe,uid=0,noforceuid,gid=0,noforcegid,addr=192.168.178.19,file_mode=0755,dir_mode=0755,iocharset=utf8,soft,nounix,serverino,mapposix,reparse=nfs,rsize=4194304,wsize=4194304,bsize=1048576,retrans=1,echo_interval=60,actimeo=1,closetimeo=1)
All mounts where configured using the remote mount Plugin and working in the CLI but don't show up in the GUI:

How can I get rid of the following mounts I can't use in OMV?
root@OMV7-02:~# ls /srv/remotemount
SYN SYN_DS218j syn_fam syn_nfs_omv SYNOLOGY_NAS
Applying the changes is not possible and after a long time show the following error:

What a mess!
After that I would have a try mounting manually via CLI.