diff --git a/backend/Dockerfile b/backend/Dockerfile
index e38531c..6c5e3a3 100644
--- a/backend/Dockerfile
+++ b/backend/Dockerfile
@@ -1,9 +1,12 @@
 FROM python:3.12-slim
 
-# Use German mirror for better connectivity and add retry logic
-RUN echo "deb http://ftp.de.debian.org/debian bookworm main" > /etc/apt/sources.list && \
-    echo "deb http://ftp.de.debian.org/debian bookworm-updates main" >> /etc/apt/sources.list && \
-    echo "Acquire::Retries \"3\";" > /etc/apt/apt.conf.d/80-retries
+# Force IPv4 and use German mirror with aggressive retry/timeout settings
+RUN echo "Acquire::ForceIPv4 \"true\";" > /etc/apt/apt.conf.d/99force-ipv4 && \
+    echo "Acquire::Retries \"5\";" > /etc/apt/apt.conf.d/80-retries && \
+    echo "Acquire::http::Timeout \"10\";" >> /etc/apt/apt.conf.d/80-retries && \
+    echo "Acquire::ftp::Timeout \"10\";" >> /etc/apt/apt.conf.d/80-retries && \
+    echo "deb http://ftp.de.debian.org/debian bookworm main" > /etc/apt/sources.list && \
+    echo "deb http://ftp.de.debian.org/debian bookworm-updates main" >> /etc/apt/sources.list
 
 # Install PostgreSQL client for psql (needed for startup.sh)
 RUN apt-get update && apt-get install -y postgresql-client && rm -rf /var/lib/apt/lists/*