Messages

It says OK.
In the instructions after installation, it said "echo 'smartd_enable="YES"' >> /etc/rc.conf"
The file did not exist.  Is this expected/normal?

Why? it's lasted me over 5 years now.  what do you use or recommend?
It doesn't look like smartctl is installed for me.

Is that ad guard home? 
Before I did the big recent upgrade (the upgrade wasn't done the same day this crashed - it has been running for some time), I did a config export.  That should have everything I need to restore, right?

The installed drive is:

Kingston Digital SSDNow UV500 mSATA 120GB (SUV500MS/120G)

SMART checks were performed from an Ubuntu Live environment.

Results:

SMART overall health: PASSED
SMART error log: No errors logged
SMART self-test: Completed without error
SATA PHY event counters:
Command failed due to ICRC error: 0
Device-to-host register FISes sent due to a COMRESET: 4

The SATA counters do not appear to indicate a failing SATA link or obvious communication problem.

Based on these results, the SSD does not currently show signs of failure. The remaining possibilities seem to be:

ZFS metadata corruption from an interrupted write/power event
OPNsense/ZFS issue during an update or shutdown
Some other filesystem/pool corruption event
Less likely, an intermittent hardware issue not caught by SMART

I am considering either:

Reinstalling OPNsense cleanly on the existing Kingston SSD and restoring only the configuration, or
Replacing the SSD anyway with a newer/larger mSATA drive (for example, a 256GB TLC mSATA drive) to provide more ZFS headroom.

At this point I am leaning toward the SSD being healthy and the issue being related to the ZFS pool state rather than a confirmed hardware failure.

Any recommendations on whether the existing pool is worth attempting further recovery on, or whether a clean reinstall is the better approach, would be appreciated.

I am running OPNsense on the FW4B Protectli appliance. The system was previously working normally.  My internet just dropped out randomly. 

Storage is a ZFS root installation:

zroot
 └── ROOT
      └── default

The system originally failed to boot with:

Mounting from zfs:zroot/ROOT/default failed with error 5
Retrying for 3 or more seconds...
Initial troubleshooting

I created a verified OPNsense 26.7 VGA amd64 USB image and booted into the live environment.

From the OPNsense live shell:

zpool import

showed the pool was detected and reported:

state: ONLINE

The pool was not initially importable because it reported:

pool was previously in use from another system
the pool can be imported using 'zpool import -f'
ZFS pool checks

I imported the pool read-only:

zpool import -f -o readonly=on zroot

The import succeeded, although mounting datasets failed because the pool was read-only:

cannot mount /zroot: failed to create mountpoint: read-only file system

import was successful, but unable to mount some datasets

After import:

zpool status -v

showed:

state: ONLINE

errors: No known data errors

The boot environment exists:

zfs list

shows:

zroot/ROOT
zroot/ROOT/default
Attempted ZFS rewind/recovery

Because the original import suggested:

recovery is possible, but will result in some data loss

approximately 2 minutes of data must be discarded

recovery can be attempted by executing:

zpool import -F zroot

I attempted:

zpool import -f -F zroot

However, this caused a system panic.

The panic message was:

KDB: enter: panic

panic: zfs(panic): zfs: rt=... adding segment.... overlapping with existing one
Current situation

After the successful read-only import, I rebooted from the internal disk.

The system now gets further into the boot process but stops at:

KDB: enter: panic
db>

Like this?
My client still doesn't have a DNS server from DHCP.  You cannot view this attachment.

I am trying to configure DNS for my clients.  I've tried configuring an upstream server in Query Forwarding and in DNS Servers in the general tab, but to no avail.  Can any one please advise on how to do so?

I am running a adguard vm.  I am trying to point my dhcp dns config to the adguard server ip.  When I check my dns server from my dhcp config on my client, it's pointing to my opnsense router.  I try to visit a website, like hp.com, and adguard does not show that the domain was queried for.  I do a nslookup hp.com <adguard-ip>, and now hp.com shows up in the query log in adguard. 
Currently, I'm pointing to the adguard server under unbound dns -> query forwarding.  I can confirm adguard is listening on port 53.

I have gone through the wizard already. 

I followed this guide: https://homenetworkguy.com/how-to/beginners-guide-to-set-up-home-network-using-opnsense/.  That should tell you what my DNS settings are. 

No, opnsense box has replaced the pfsense device.  I switch between the devices until I can get this working.

I pinged 9.9.9.9 from my phone, connected to a cell tower, to confirm that it responds to ping.  That was not a client on my network.
I get no response.  But when I do packet capture, I see echo replies.
Client computers can not access the internet.  My opnsense box also has issues (ie checking for updates, fails).  Something like name resolution.
My box is an old desktop.
It is a placeholder for my current pfsense box.  I didn't wanna wipe my pfsense box till I was 100% sure I got the config right, and secured.
I will post the firewall rules for lan and wan.
https://ibb.co/kMfYcs5
https://ibb.co/rMMqzhR

Internet -> Modem -> opnsense box -> switch -> end client machine.

I'm not sure what else to describe.  I think ping is one of the most basic tests.  If I can't get out/ping, then it's not worth it to go any further.

I've been using pfsense up until now.  I would say I'm pretty knowledgeable, including dhcp, dns, and ports, as well as firewall rules. 
Yes, this is a residential setup.
Let me know if there are any other screenshots of settings you'd like to see.