diff --git a/docs/administration-guide.rst b/docs/administration-guide.rst
index 1b1155a5..c270bdb1 100644
--- a/docs/administration-guide.rst
+++ b/docs/administration-guide.rst
@@ -737,6 +737,9 @@ on the backup server.
 The default value for ``username`` ist ``root@pam``.  If no server is specified,
 the default is the local host (``localhost``).
 
+Note that if the server is an IPv6 address, you have to write it with
+square brackets (e.g. [fe80::01]).
+
 You can pass the repository with the ``--repository`` command
 line option, or by setting the ``PBS_REPOSITORY`` environment
 variable.
diff --git a/src/api2/types/mod.rs b/src/api2/types/mod.rs
index aba307e2..6ad67607 100644
--- a/src/api2/types/mod.rs
+++ b/src/api2/types/mod.rs
@@ -3,7 +3,7 @@ use serde::{Deserialize, Serialize};
 
 use proxmox::api::{api, schema::*};
 use proxmox::const_regex;
-use proxmox::{IPRE, IPV4RE, IPV6RE, IPV4OCTET, IPV6H16, IPV6LS32};
+use proxmox::{IPRE, IPRE_BRACKET, IPV4RE, IPV6RE, IPV4OCTET, IPV6H16, IPV6LS32};
 
 use crate::backup::CryptMode;
 use crate::server::UPID;
@@ -65,7 +65,7 @@ const_regex!{
 
     pub DNS_NAME_OR_IP_REGEX = concat!(r"^", DNS_NAME!(), "|",  IPRE!(), r"$");
 
-    pub BACKUP_REPO_URL_REGEX = concat!(r"^^(?:(?:(", USER_ID_REGEX_STR!(), ")@)?(", DNS_NAME!(), "|",  IPRE!() ,"):)?(", PROXMOX_SAFE_ID_REGEX_STR!(), r")$");
+    pub BACKUP_REPO_URL_REGEX = concat!(r"^^(?:(?:(", USER_ID_REGEX_STR!(), ")@)?(", DNS_NAME!(), "|",  IPRE_BRACKET!() ,"):)?(", PROXMOX_SAFE_ID_REGEX_STR!(), r")$");
 
     pub CERT_FINGERPRINT_SHA256_REGEX = r"^(?:[0-9a-fA-F][0-9a-fA-F])(?::[0-9a-fA-F][0-9a-fA-F]){31}$";