Fish protocol isn't working

Hi all!
After setting up LEDE on my router, one of the first things I tried to do, to have easier access to the configuration files, was setting up a network folder in KDE.
Unfortunately, it seems that LEDE's implementation of SSH doesn't support the fish protocol somehow.

I've googled around but there's a lot of messy information out there... someone blames dropbear, someone blames busybox... in the end I haven't been able to determine the culprit and/or to find the fix.

Does anybody else have this problem? Workarounds?

Thank you in advance.

have you tried to install the openssh-server?

No, I did not try, mainly because of space restrictions.
But now that I extended my root partition using an USB drive I can try that!

Thank you!