Wireless (& wired) network issues/instability

Hi, I just installed OpenMediaVault for the first time a few days ago and I keep having problems with the network.
After failing to install from a USB flash drive, due to issues with grub (caused, I suspect, by the fact that I use a NVMe SSD as system drive), I hooked up a DVD drive and successfully installed from there (although I had to install grub manually). During the install, I had the option to use all the network interfaces expected on my ASRock H270M-ITX/AC motherboard, i.e. eth0, eth1 and wlan0. I chose wlan0, since it is the one I intend to be using mainly, connected and was able to use the connection throughout the installation successfully.
However, once I booted the system, there was no internet and when I looked into /etc/network/interfaces, there was only the loopback interface there. I added the eth0 interface, which meant that I was able to connect via ethernet, and then added the wlan0 interface along with the ssid and password from the web interface.
When I rebooted, there was still no wireless connection. I tried following the installation guide on the Debian Wiki. iwlwifi seemed to be already installed correctly, but when i run the modprobe command I get an error:

# modprobe -r iwlwifi ; modprobe iwlwifi
[ 1535.681171] iwlwifi 0000:03:00.0: firmware: fialed to load iwlwifi-3160-17.ucode

I looked in the /lib/firmware folder and saw several iwlwifi-3160-*.ucode files there, but the highest version was 9 (i.e. iwlwifi-3160-9.ucode) if I remember correctly.
At that point, I though I was just missing the correct iwlwifi driver, as it said it couldn't find the iwlwifi-3160-17.ucode file. I finally managed to connect by manually downloading the iwlwifi-3160-17.ucode file from the internet (this page only had earlier versions, so I got the version 17 off of somebody's github here) and putting it into the /lib/firmware folder.

My /etc/network/interfaces currently look like this:

# The loopback network interface
auto lo
iface lo inet loopback
iface lo inet6 loopback


# wlan0 network interface
auto wlan0
allow-hotplug wlan0
iface wlan0 inet dhcp
    wpa-ssid MYSSID
    wpa-key-mgmt WPA-PSK
    wpa-psk MYPASSWORD
iface wlan0 inet6 dhcp
    pre-up echo 1 > /proc/sys/net/ipv6/conf/$IFACE/accept_ra
    pre-up echo 0 > /proc/sys/net/ipv6/conf/$IFACE/disable_ipv6


# ethernet 0 network interface
auto eth0
allow-hotplug eth0
iface eth0 inet dhcp


# ethernet 1 network interface
auto eth1
allow-hotplug eth1
iface eth0 inet dhcp

So my current state is that I am able to connect, but it is far from stable. During boot it takes well over a minute to bring up the network interface and sometimes it doesn't come up at all. One afternoon, the wifi would only work if I had the ethernet cable connected as well. Other times, after several hours, it just disconnects and I have to reboot. Sometimes a few times before it connects again.

Now my main questions are these:
1. Am I doing something fundamentally wrong or is this the way it should be setup?
2. Why wasn't the wifi interface available right after installation?
3. Is there any guide on how to setup the network properly? (I didn't find one.)
4. Is there a way to make the system try to automatically reconnect, in case the wifi drops, so that I don't need to reboot each time?

Also to note: when I use the web interface and don't do anything for a couple of minutes, it always says "software error". I have to refresh and login again. Is that the expected behaviour? (No such issues with ssh.)

Any help would be greatly appreciated. Thanks in advance.

PS: I am not a very experienced linux user, so please feel free to point out even the most basic things

I realize this is the easy solution, and that a wire is always gonna be more reliable than wifi. However, since all the necessary tech is there, I am curious if it is possible to set it up in a reliable way. Also, while not a problem for me to connect via ethernet, it might not be the case for others, so I think it would be generally beneficial to have this alternative.

Even though I said I am not very experienced, I am open to experimentation and certainly willing to learn.

Since I didn't really get any feedback on how to deal with the wireless issues, aside from "don't use it", I continued investigating myself and was somewhat successfull, so I thought I'd share my progress.

Following my own original questions:

1. As far as I can tell from the available debian resources, the way I set up my network is generally correct. Apparently, there are more modern ways to do it, such as using the NetworkManager, however, I am not sure whether these are applicable to systems without gui environment and the interfaces were working, I didn't wanna waste time learning it. That being said, my /etc/network/interfaces file is now a bit simpler and more secure, as I replaced the wifi password with a wpa psk generated with the command  wpa_passphrase MYSSID MYPASSWORD , so the full contents are

# The loopback network interface
auto lo
iface lo inet loopback
iface lo inet6 loopback


# wlan0 network interface
auto wlan0
iface wlan0 inet dhcp
    wpa-ssid "domov"
    wpa-psk MYWPAPSK


# ethernet 0 network interface
auto eth0
allow-hotplug eth0
iface eth0 inet dhcp


# ethernet 1 network interface
auto eth1
allow-hotplug eth1
iface eth0 inet dhcp

Unfortunately, I don't have any progress on points 2. and 3. so any info towards these is greatly appreciated.

4. Here I believe I have found a nice solution, credit for which goes here and here.
It lies in creating a script whichchecks whether the wlan0 interface is alive and if not,restarts it. The script is run every 5 minutes using cron. The script, which i saved as /usr/local/bin/wlan_checker.sh is the following

#!/bin/bash


# The IP for the server you wish to ping
#SERVER=8.8.8.8  # A public Google DNS server IP
SERVER=192.168.0.1  # Router IP


# Only send two pings, sending output to /dev/null
/bin/ping -I wlan0 -c2 ${SERVER} > /dev/null


# If the return code from ping ($?) is not 0 (meaning there was an error)
if [ $? != 0 ]
then
    # Restart the wireless interface
    /sbin/ifdown --force wlan0
    /sbin/ifup wlan0
fi

and the crontab entry for it (added by running crontab -e is

*/5 * * * * /bin/bash /usr/local/bin/wlan_checker.sh

According to my testing so far, this seems to keep the wlan0 interface up and running. I'd like to note though, that in case you are saving same data on your NAS, to which you absolutely need to have access all the time, you are still probably better of using ethernet. Also, unless both your motherboard and router support ac wifi (my mobo does, but router doesn't), your speed is gonna be a lot slower even than a 100 Mbit ethernet.

Hope this helps