user41612: I checked several related posts but couldn't solve my problem.
I have Antergos Linux :
# uname -a
Linux biutitude 4.14.11-1-ARCH #1 SMP PREEMPT Wed Jan 3 07:02:42 UTC 2018 x86_64 GNU/Linux

The board is a Seeeduino Lorawan.
The problem is that the menu to select the port is greyed, and when I check in /dev I don't see any new tty when I plug the card. However the card blinks.
I tried :
- adding myself to lock + tty + uucp (and restarted my session)
- created a dialout group because I didn't have one, added myself to it
- loading cdc_acm module but got the following error :
# modprobe cdc_acm
modprobe: FATAL: Module cdc_acm not found in directory /lib/modules/4.14.11-1-ARCH

Thus I tried : 
[root@biutitude biu]# depmod -ae
depmod: WARNING: -e needs -E or -F
depmod: ERROR: could not open directory /lib/modules/4.14.11-1-ARCH: No such file or directory
depmod: FATAL: could not search modules: No such file or directory
[root@biutitude biu]# depmod
depmod: ERROR: could not open directory /lib/modules/4.14.11-1-ARCH: No such file or directory
depmod: FATAL: could not search modules: No such file or directory

I'm clearly out of ideas. The weirdest is that a few months ago, I was able to use a RFduino card without any trouble.

user81602: My solution - install linux-modules-extra kernel module on ubuntu 20.04. Solved my problem which was identical.
Get OS details:
uname -a
Linux seeeduino-node 5.4.0-91-generic #102-Ubuntu SMP Fri Nov 5 16:31:28 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Install the sudo apt install linux-modules-extra:
sudo apt install linux-modules-extra-<kernel-version>

Example:
sudo apt install linux-modules-extra-5.4.0-91-generic

You need to reboot the machine afterwards it should work.

41612: <p>I checked several related posts but couldn't solve my problem.</p>

<p>I have Antergos Linux :</p>

<pre><code># uname -a
Linux biutitude 4.14.11-1-ARCH #1 SMP PREEMPT Wed Jan 3 07:02:42 UTC 2018 x86_64 GNU/Linux
</code></pre>

<p>The board is a Seeeduino Lorawan.</p>

<p>The problem is that the menu to select the port is greyed, and when I check in /dev I don't see any new tty when I plug the card. However the card blinks.</p>

<p>I tried :
- adding myself to lock + tty + uucp (and restarted my session)
- created a dialout group because I didn't have one, added myself to it
- loading cdc_acm module but got the following error :</p>

<pre><code># modprobe cdc_acm
modprobe: FATAL: Module cdc_acm not found in directory /lib/modules/4.14.11-1-ARCH
</code></pre>

<p>Thus I tried : </p>

<pre><code>[root@biutitude biu]# depmod -ae
depmod: WARNING: -e needs -E or -F
depmod: ERROR: could not open directory /lib/modules/4.14.11-1-ARCH: No such file or directory
depmod: FATAL: could not search modules: No such file or directory
[root@biutitude biu]# depmod
depmod: ERROR: could not open directory /lib/modules/4.14.11-1-ARCH: No such file or directory
depmod: FATAL: could not search modules: No such file or directory
</code></pre>

<p>I'm clearly out of ideas. The weirdest is that a few months ago, I was able to use a RFduino card without any trouble.</p>
 81602: <p>My solution - install linux-modules-extra kernel module on ubuntu 20.04. Solved my problem which was identical.</p>
<p>Get OS details:</p>
<pre><code>uname -a
Linux seeeduino-node 5.4.0-91-generic #102-Ubuntu SMP Fri Nov 5 16:31:28 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
</code></pre>
<p>Install the sudo apt install linux-modules-extra:</p>
<pre><code>sudo apt install linux-modules-extra-&lt;kernel-version&gt;
</code></pre>
<p>Example:</p>
<pre><code>sudo apt install linux-modules-extra-5.4.0-91-generic
</code></pre>
<p>You need to reboot the machine afterwards it should work.</p>
