GPG error

[gabriel-lucas]

Updating Debian 9.3 it states this error:

W: GPG error: http://repo.clommunity-project.eu/debian unstable/ Release: The following signatures were invalid: C7C294DD25129E9DCDFA69A9D246F495A59C5DC8

Could be related to this?
https://unix.stackexchange.com/questions/387053/debian-9-apt-and-gpg-error-inrelease-the-following-signatures-were-inva

Log:
apt-get update
Ign:1 http://ftp.es.debian.org/debian stretch InRelease
Ign:2 http://serveis.guifi.net/debian guifi/ InRelease
Get:3 http://security.debian.org/debian-security stretch/updates InRelease [63.0 kB]
Get:4 http://ftp.debian.org/debian stretch-backports InRelease [91.8 kB]
Hit:5 http://serveis.guifi.net/debian guifi/ Release
Get:6 http://ftp.es.debian.org/debian stretch-updates InRelease [91.0 kB]
Hit:7 http://ftp.es.debian.org/debian stretch Release
Get:9 http://security.debian.org/debian-security stretch/updates/main Sources [109 kB]
Get:10 http://security.debian.org/debian-security stretch/updates/main amd64 Packages [270 kB]
Get:11 http://security.debian.org/debian-security stretch/updates/main Translation-en [119 kB]
Get:12 http://ftp.debian.org/debian stretch-backports/main Translation-en.diff/Index [27.8 kB]
Get:13 http://ftp.debian.org/debian stretch-backports/main Translation-en 2018-02-07-0231.38.pdiff [371 B]
Get:13 http://ftp.debian.org/debian stretch-backports/main Translation-en 2018-02-07-0231.38.pdiff [371 B]
Ign:15 http://repo.clommunity-project.eu/debian unstable/ InRelease
Hit:16 http://repo.clommunity-project.eu/debian unstable/ Release
Get:17 http://repo.clommunity-project.eu/debian unstable/ Release.gpg [543 B]
Ign:17 http://repo.clommunity-project.eu/debian unstable/ Release.gpg
Fetched 773 kB in 6s (126 kB/s)
Reading package lists... Done
W: GPG error: http://repo.clommunity-project.eu/debian unstable/ Release: The following signatures were invalid: C7C294DD25129E9DCDFA69A9D246F495A59C5DC8
W: The repository 'http://repo.clommunity-project.eu/debian unstable/ Release' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.