diff --git a/fireflyiii/CHANGELOG.md b/fireflyiii/CHANGELOG.md
index 06690d22d0..bcdb522dc5 100644
--- a/fireflyiii/CHANGELOG.md
+++ b/fireflyiii/CHANGELOG.md
@@ -1,4 +1,7 @@
 
+## 6.6.2-1 (2026-05-10)
+- Fix MariaDB connection on HAOS >=17.3 by forcing IPv4 host resolution (#2688)
+
 ## 6.6.2 (2026-05-02)
 - Update to latest version from firefly-iii/firefly-iii (changelog : https://github.com/firefly-iii/firefly-iii/releases)
 
diff --git a/fireflyiii/config.yaml b/fireflyiii/config.yaml
index 82e84e17a3..95d1f1338c 100644
--- a/fireflyiii/config.yaml
+++ b/fireflyiii/config.yaml
@@ -104,5 +104,5 @@ slug: fireflyiii
 startup: services
 udev: true
 url: https://github.com/alexbelgium/hassio-addons
-version: "6.6.2"
+version: "6.6.2-1"
 webui: "[PROTO:ssl]://[HOST]:[PORT:8080]"
diff --git a/fireflyiii/rootfs/etc/cont-init.d/99-run.sh b/fireflyiii/rootfs/etc/cont-init.d/99-run.sh
index d8be95a51c..bb4757f4fa 100755
--- a/fireflyiii/rootfs/etc/cont-init.d/99-run.sh
+++ b/fireflyiii/rootfs/etc/cont-init.d/99-run.sh
@@ -86,9 +86,18 @@ case $(bashio::config 'DB_CONNECTION') in
                 "Please ensure it is installed and started"
         fi
 
+        # Resolve MariaDB hostname to IPv4: on HAOS >=17.3 the Supervisor network
+        # gained IPv6, but the MariaDB addon only grants its user from the IPv4
+        # subnet (issue #2688). Fall back to the raw hostname if resolution fails.
+        mariadb_host_raw="$(bashio::services "mysql" "host")"
+        mariadb_host_ipv4="$(getent ahostsv4 "$mariadb_host_raw" 2> /dev/null | awk '{print $1; exit}')"
+        DB_HOST="${mariadb_host_ipv4:-$mariadb_host_raw}"
+        if [ "$DB_HOST" != "$mariadb_host_raw" ]; then
+            bashio::log.info "Resolved ${mariadb_host_raw} -> ${DB_HOST} (forcing IPv4)"
+        fi
+
         # Use values
         DB_CONNECTION=mysql
-        DB_HOST=$(bashio::services "mysql" "host")
         DB_PORT=$(bashio::services "mysql" "port")
 
         # Always fetch service discovery credentials for bootstrap operations (CREATE DATABASE)
diff --git a/monica/CHANGELOG.md b/monica/CHANGELOG.md
index 68a49bafbc..d70dfecbfa 100644
--- a/monica/CHANGELOG.md
+++ b/monica/CHANGELOG.md
@@ -1,3 +1,6 @@
+## 5.0.0b5-3 (2026-05-10)
+- Fix MariaDB connection on HAOS >=17.3 by forcing IPv4 host resolution (#2688)
+
 ## 5.0.0b5-2 (26-02-2026)
 - Minor bugs fixed
 
diff --git a/monica/config.yaml b/monica/config.yaml
index e5ea8ec1a3..fc59d9801b 100644
--- a/monica/config.yaml
+++ b/monica/config.yaml
@@ -108,5 +108,5 @@ services:
   - mysql:want
 slug: monica
 url: https://github.com/alexbelgium/hassio-addons/tree/master/monica
-version: "5.0.0b5-2"
+version: "5.0.0b5-3"
 webui: "[PROTO:ssl]://[HOST]:[PORT:80]"
diff --git a/monica/rootfs/etc/cont-init.d/99-run.sh b/monica/rootfs/etc/cont-init.d/99-run.sh
index fc0a122a72..232ec75112 100755
--- a/monica/rootfs/etc/cont-init.d/99-run.sh
+++ b/monica/rootfs/etc/cont-init.d/99-run.sh
@@ -45,8 +45,18 @@ case "$database" in
             bashio::exit.nok "Please ensure it is installed and started"
         fi
 
+        # Resolve MariaDB hostname to IPv4: on HAOS >=17.3 the Supervisor network
+        # gained IPv6, but the MariaDB addon only grants its user from the IPv4
+        # subnet (issue #2688). Fall back to the raw hostname if resolution fails.
+        mariadb_host_raw="$(bashio::services "mysql" "host")"
+        mariadb_host_ipv4="$(getent ahostsv4 "$mariadb_host_raw" 2> /dev/null | awk '{print $1; exit}')"
+        DB_HOST="${mariadb_host_ipv4:-$mariadb_host_raw}"
+        if [ "$DB_HOST" != "$mariadb_host_raw" ]; then
+            bashio::log.info "Resolved ${mariadb_host_raw} -> ${DB_HOST} (forcing IPv4)"
+        fi
+
         # Use values
-        DB_HOST=$(bashio::services "mysql" "host") && bashio::log.blue "DB_HOST=$DB_HOST" && sed -i "1a export DB_HOST=$DB_HOST" /usr/local/bin/entrypoint.sh
+        bashio::log.blue "DB_HOST=$DB_HOST" && sed -i "1a export DB_HOST=$DB_HOST" /usr/local/bin/entrypoint.sh
         DB_PORT=$(bashio::services "mysql" "port") && bashio::log.blue "DB_PORT=$DB_PORT" && sed -i "1a export DB_PORT=$DB_PORT" /usr/local/bin/entrypoint.sh
         DB_DATABASE=monica && bashio::log.blue "DB_DATABASE=$DB_DATABASE" && sed -i "1a export DB_DATABASE=$DB_DATABASE" /usr/local/bin/entrypoint.sh
         DB_USERNAME=$(bashio::services "mysql" "username") && bashio::log.blue "DB_USERNAME=$DB_USERNAME" && sed -i "1a export DB_USERNAME=$DB_USERNAME" /usr/local/bin/entrypoint.sh
diff --git a/photoprism/CHANGELOG.md b/photoprism/CHANGELOG.md
index 38ddfede47..98c4f8fac8 100644
--- a/photoprism/CHANGELOG.md
+++ b/photoprism/CHANGELOG.md
@@ -1,4 +1,7 @@
 
+## ubuntu-2026-03-05-1 (2026-05-10)
+- Fix MariaDB connection on HAOS >=17.3 by forcing IPv4 host resolution (#2688)
+
 ## ubuntu-2026-03-05 (2026-03-05)
 - Update to latest version from photoprism/photoprism
 ## ubuntu-2025-11-30-4 (26-02-2026)
diff --git a/photoprism/config.yaml b/photoprism/config.yaml
index fa50c736cd..6443154f63 100644
--- a/photoprism/config.yaml
+++ b/photoprism/config.yaml
@@ -131,5 +131,5 @@ services:
 slug: photoprism
 udev: true
 url: https://github.com/alexbelgium/hassio-addons
-version: "ubuntu-2026-03-05"
+version: "ubuntu-2026-03-05-1"
 video: true
diff --git a/photoprism/rootfs/etc/cont-init.d/99-run.sh b/photoprism/rootfs/etc/cont-init.d/99-run.sh
index 68b566a079..ca2f639771 100755
--- a/photoprism/rootfs/etc/cont-init.d/99-run.sh
+++ b/photoprism/rootfs/etc/cont-init.d/99-run.sh
@@ -28,9 +28,20 @@ case $(bashio::config 'DB_TYPE') in
         # Install mysqlclient
         pip install pymysql &> /dev/null || true
 
+        # Resolve MariaDB hostname to IPv4: on HAOS >=17.3 the Supervisor network
+        # gained IPv6, but the MariaDB addon only grants its user from the IPv4
+        # subnet (issue #2688). Fall back to the raw hostname if resolution fails.
+        mariadb_host_raw="$(bashio::services 'mysql' 'host')"
+        mariadb_host_ipv4="$(getent ahostsv4 "$mariadb_host_raw" 2> /dev/null | awk '{print $1; exit}')"
+        mariadb_host="${mariadb_host_ipv4:-$mariadb_host_raw}"
+        if [ "$mariadb_host" != "$mariadb_host_raw" ]; then
+            bashio::log.info "Resolved ${mariadb_host_raw} -> ${mariadb_host} (forcing IPv4)"
+        fi
+        mariadb_port="$(bashio::services 'mysql' 'port')"
+
         # Use values
         PHOTOPRISM_DATABASE_DRIVER="mysql"
-        PHOTOPRISM_DATABASE_SERVER="$(bashio::services 'mysql' 'host'):$(bashio::services 'mysql' 'port')"
+        PHOTOPRISM_DATABASE_SERVER="${mariadb_host}:${mariadb_port}"
         PHOTOPRISM_DATABASE_NAME="photoprism"
         PHOTOPRISM_DATABASE_USER="$(bashio::services 'mysql' 'username')"
         PHOTOPRISM_DATABASE_PASSWORD="$(bashio::services 'mysql' 'password')"
@@ -58,9 +69,9 @@ case $(bashio::config 'DB_TYPE') in
         bashio::log.warning "Uninstalling the MariaDB addon will remove any data"
 
         # Create database
-        mysql --skip-ssl --host="$(bashio::services 'mysql' 'host')" --port="$(bashio::services 'mysql' 'port')" --user="$PHOTOPRISM_DATABASE_USER" --password="$PHOTOPRISM_DATABASE_PASSWORD" -e"CREATE DATABASE IF NOT EXISTS $PHOTOPRISM_DATABASE_NAME;"
+        mysql --skip-ssl --host="${mariadb_host}" --port="${mariadb_port}" --user="$PHOTOPRISM_DATABASE_USER" --password="$PHOTOPRISM_DATABASE_PASSWORD" -e"CREATE DATABASE IF NOT EXISTS $PHOTOPRISM_DATABASE_NAME;"
         # Force character set
-        mysql --skip-ssl --host="$(bashio::services 'mysql' 'host')" --port="$(bashio::services 'mysql' 'port')" --user="$PHOTOPRISM_DATABASE_USER" --password="$PHOTOPRISM_DATABASE_PASSWORD" -e"ALTER DATABASE $PHOTOPRISM_DATABASE_NAME CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci;" || true
+        mysql --skip-ssl --host="${mariadb_host}" --port="${mariadb_port}" --user="$PHOTOPRISM_DATABASE_USER" --password="$PHOTOPRISM_DATABASE_PASSWORD" -e"ALTER DATABASE $PHOTOPRISM_DATABASE_NAME CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci;" || true
         ;;
 esac
 
diff --git a/seafile/CHANGELOG.md b/seafile/CHANGELOG.md
index 7b21add428..48b98f2d96 100644
--- a/seafile/CHANGELOG.md
+++ b/seafile/CHANGELOG.md
@@ -1,4 +1,7 @@
 
+## 12.0.18-3 (2026-05-10)
+- Fix MariaDB connection on HAOS >=17.3 by forcing IPv4 host resolution (#2688)
+
 ## 12.0.18-2 (2026-02-22)
 - Fix download URLs containing incorrect `/seafhttp` prefix on first run by re-applying URL configuration after upstream init scripts complete.
 
diff --git a/seafile/config.yaml b/seafile/config.yaml
index 4cca056bbe..2dc5ab8b2e 100644
--- a/seafile/config.yaml
+++ b/seafile/config.yaml
@@ -128,5 +128,5 @@ services:
 slug: seafile
 udev: true
 url: https://github.com/alexbelgium/hassio-addons/tree/master/seafile
-version: "12.0.18-2"
+version: "12.0.18-3"
 webui: http://[HOST]:[PORT:8000]
diff --git a/seafile/rootfs/etc/cont-init.d/99-run.sh b/seafile/rootfs/etc/cont-init.d/99-run.sh
index d0e08cc72a..242504217d 100755
--- a/seafile/rootfs/etc/cont-init.d/99-run.sh
+++ b/seafile/rootfs/etc/cont-init.d/99-run.sh
@@ -206,8 +206,18 @@ case "${DATABASE_SELECTION}" in
                 "Please ensure it is installed and started"
         fi
 
+        # Resolve MariaDB hostname to IPv4: on HAOS >=17.3 the Supervisor network
+        # gained IPv6, but the MariaDB addon only grants its user from the IPv4
+        # subnet (issue #2688). Fall back to the raw hostname if resolution fails.
+        mariadb_host_raw="$(bashio::services 'mysql' 'host')"
+        mariadb_host_ipv4="$(getent ahostsv4 "$mariadb_host_raw" 2> /dev/null | awk '{print $1; exit}')"
+        MYSQL_HOST_RESOLVED="${mariadb_host_ipv4:-$mariadb_host_raw}"
+        if [ "$MYSQL_HOST_RESOLVED" != "$mariadb_host_raw" ]; then
+            bashio::log.info "Resolved ${mariadb_host_raw} -> ${MYSQL_HOST_RESOLVED} (forcing IPv4)"
+        fi
+
         # Use values
-        export MYSQL_HOST="$(bashio::services 'mysql' 'host')" && sed -i "1a export MYSQL_HOST=$(bashio::services 'mysql' 'host')" /home/seafile/*.sh
+        export MYSQL_HOST="$MYSQL_HOST_RESOLVED" && sed -i "1a export MYSQL_HOST=${MYSQL_HOST_RESOLVED}" /home/seafile/*.sh
         export MYSQL_PORT="$(bashio::services 'mysql' 'port')" && sed -i "1a export MYSQL_PORT=$(bashio::services 'mysql' 'port')" /home/seafile/*.sh
         export MYSQL_USER="$(bashio::services "mysql" "username")" && sed -i "1a export MYSQL_USER=$(bashio::services 'mysql' 'username')" /home/seafile/*.sh
         export MYSQL_USER_PASSWD="$(bashio::services "mysql" "password")" && sed -i "1a export MYSQL_USER_PASSWD=$(bashio::services 'mysql' 'password')" /home/seafile/*.sh
diff --git a/zoneminder/CHANGELOG.md b/zoneminder/CHANGELOG.md
index 9c096947aa..68225158ed 100644
--- a/zoneminder/CHANGELOG.md
+++ b/zoneminder/CHANGELOG.md
@@ -1,4 +1,7 @@
 
+## 1.38.1-1 (2026-05-10)
+- Fix MariaDB connection on HAOS >=17.3 by forcing IPv4 host resolution (#2688)
+
 ## 1.38.1 (2026-02-21)
 - Update to latest version from zoneminder-containers/zoneminder-base (changelog : https://github.com/zoneminder-containers/zoneminder-base/releases)
 
diff --git a/zoneminder/config.yaml b/zoneminder/config.yaml
index d7a62d6b94..16443c5389 100644
--- a/zoneminder/config.yaml
+++ b/zoneminder/config.yaml
@@ -95,5 +95,5 @@ services:
 slug: zoneminder
 udev: true
 url: https://github.com/alexbelgium/hassio-addons
-version: "1.38.1"
+version: "1.38.1-1"
 webui: "[PROTO:ssl]://[HOST]:[PORT:80]/zm"
diff --git a/zoneminder/rootfs/etc/cont-init.d/99-run.sh b/zoneminder/rootfs/etc/cont-init.d/99-run.sh
index 701fb6a039..9c2330a719 100755
--- a/zoneminder/rootfs/etc/cont-init.d/99-run.sh
+++ b/zoneminder/rootfs/etc/cont-init.d/99-run.sh
@@ -31,7 +31,16 @@ case "$(bashio::config "DB_CONNECTION")" in
 
         DB_CONNECTION="mysql"
         remoteDB="1"
-        ZM_DB_HOST="$(bashio::services "mysql" "host")"
+
+        # Resolve MariaDB hostname to IPv4: on HAOS >=17.3 the Supervisor network
+        # gained IPv6, but the MariaDB addon only grants its user from the IPv4
+        # subnet (issue #2688). Fall back to the raw hostname if resolution fails.
+        mariadb_host_raw="$(bashio::services "mysql" "host")"
+        mariadb_host_ipv4="$(getent ahostsv4 "$mariadb_host_raw" 2> /dev/null | awk '{print $1; exit}')"
+        ZM_DB_HOST="${mariadb_host_ipv4:-$mariadb_host_raw}"
+        if [ "$ZM_DB_HOST" != "$mariadb_host_raw" ]; then
+            bashio::log.info "Resolved ${mariadb_host_raw} -> ${ZM_DB_HOST} (forcing IPv4)"
+        fi
         ZM_DB_PORT="$(bashio::services "mysql" "port")"
         ZM_DB_NAME="zm"
         ZM_DB_USER="$(bashio::services "mysql" "username")"