at first, sorry for my late reply. I have been quite busy lately.
I have read quite a lot on this subject and it seems to be a common issue with mainly Arch. I found one post though on Debian with unclear root cause analysis, except that it might be connected to sytemd (Debian post)
I have used many of the tricks listed in the good Arch wiki in NFS (ArchWiki). Playing around with options or automatic mount handling service scripts have not helped so much. I might have missed something though in the way to activate the services or to tweak them for my environment.
At the end, I read more in detail your own script (should have done that earlier but needed to gather more knowledge on this topic first). Then, I noticed you use the soft option when you mount your folder. It is actually the key point solving this issue despite it is not recommended to use it.
Hence, by using following in /etc/fstab, my issue is solved. There is no need to create additional service:
192.168.0.30:/home/server_folder /mnt/client_folder nfs4 soft,noauto,x-systemd.automount,x-systemd.device-timeout=10,timeo=14 0 0
Again, what is key here is the option soft. The rest is based on the advise of the ArchWiki above.
I have another family desktop computer running Linux Mint (I prefer of course Antergos on my laptop ) and I don’t have any issue with the NFS client, without having to use the option soft.
It sounds to me to be an Arch “bug”, maybe connected to systemd integration. Hope one day someone will solve that.
See you around.