Why did you not include the folder before /backup/?

It should be :

server:/export/backup/system/pc1 /backup/system nfs4 auto,noatime 0 0 

You need to mount it according to your export file.

Edit :

Could it be that you are exporting the file pc1 only to the IP address 192.168.1.8 and your client does not have that IP.

Try changing the IP address :

/export/backup/system/pc1 192.168.1.0/24(rw,sync,no_root_squash,no_subtree_check) 

Does not apply to NFSv4:

Why did you not include the folder before /backup/?

It should be :

server:/export/backup/system/pc1 /backup/system nfs4 auto,noatime 0 0 

You need to mount it according to your export file.

Edit :

Could it be that you are exporting the file pc1 only to the IP address 192.168.1.8 and your client does not have that IP.

Try changing the IP address :

/export/backup/system/pc1 192.168.1.0/24(rw,sync,no_root_squash,no_subtree_check) 

Why did you not include the folder before /backup/?

It should be :

server:/export/backup/system/pc1 /backup/system nfs4 auto,noatime 0 0 

You need to mount it according to your export file.

Why did you not include the folder before /backup/?

It should be :

server:/export/backup/system/pc1 /backup/system nfs4 auto,noatime 0 0 

You need to mount it according to your export file.

Edit :

Could it be that you are exporting the file pc1 only to the IP address 192.168.1.8 and your client does not have that IP.

Try changing the IP address :

/export/backup/system/pc1 192.168.1.0/24(rw,sync,no_root_squash,no_subtree_check)