Question: As probably with most of the world, my cable modem experiences downtime intermittently each day (for maybe several minutes).

The problem is, I use my cable modem for DHCP - I have a switch connected to one of it's LAN outputs and have a number of computers connected to the switch. Everything is wired, no wireless.

When the cable modem experiences an ISP issue (for whatever reason), then my entire home LAN becomes inaccessible - I cannot ping one of my linux machines to another, my Samba shares are not accessible, and so forth.

I understand of course that I cannot make connections to the internet, but I was hoping at least my home LAN would be unaffected (i.e. home machine A communicating with home machine B).

Would anyone have suggestions on how I can insulate my home LAN operation from intermittent outages in my cable modem for the internet?

Thanks, I appreciate.

Answer: 
If the disk is not mounting, then you will likely have to spend some money on
a repair utility or a data recovery application, if the data is important and
has no backup.

Although you have specified that you are not interested
in commercial software, I list below some such tools, if no better answer
comes up. You may ask around your friends or nearby repair-shops that might
have one of the below-mentioned products, which you may use freely or
at least cheaply.
These products have demo versions that you can try to see how effective they
would be, to see if they are worth searching for (or buying).

[Stellar Data Recovery](https://www.stellarinfo.com/free-mac-data-recovery.php)
has a demo version that will recover up to 1 GB of lost or deleted data, free of cost.
The full version will cost €79.

[Data Rescue](https://www.prosofteng.com/mac-data-recovery)
by Prosoft Engineering has straight recovery options, but also
advanced options to try to recover data from disks with physical failures.
It has a demo version and has an interesting pricing model, where the
price is determined by the amount of data that you wish to recover,
starting from as low as $19.

[DiskWarrior](https://www.alsoft.com/)
has a data recovery type option - it will try to rebuild and present
a preview of what it thinks should be on the disk even if it can’t repair,
and it might allow you to copy the data off. It is very costly at $119.95.

[EaseUS Data Recovery Wizard for Mac](https://www.easeus-software.com/data-recovery-software/mac-data-recovery-wizard.html)
is a subscription product, starting from $89.95 per year.
Another tool that is available is [**Disk Drill**](https://www.cleverfiles.com/pro.html), it has tree editions

![enter image description here](https://i.stack.imgur.com/TWaPQ.png)