diff --git a/tests/net/6lo/testcase.yaml b/tests/net/6lo/testcase.yaml
index 552f31c38e6..e1310707049 100644
--- a/tests/net/6lo/testcase.yaml
+++ b/tests/net/6lo/testcase.yaml
@@ -9,3 +9,7 @@ tests:
   net.6lo.preempt:
     extra_configs:
       - CONFIG_NET_TC_THREAD_PREEMPTIVE=y
+  net.6lo.variable_buf_size:
+    extra_configs:
+      - CONFIG_NET_BUF_VARIABLE_DATA_SIZE=y
+      - CONFIG_NET_BUF_DATA_POOL_SIZE=4096
diff --git a/tests/net/ipv6/testcase.yaml b/tests/net/ipv6/testcase.yaml
index e92430af229..804ec02fb8e 100644
--- a/tests/net/ipv6/testcase.yaml
+++ b/tests/net/ipv6/testcase.yaml
@@ -1,4 +1,11 @@
+common:
+  tags: net ipv6
+  depends_on: netif
 tests:
   net.ipv6:
-    tags: net ipv6
-    depends_on: netif
+    extra_configs:
+      - CONFIG_NET_BUF_FIXED_DATA_SIZE=y
+  net.ipv6.variable_buf_size:
+    extra_configs:
+      - CONFIG_NET_BUF_VARIABLE_DATA_SIZE=y
+      - CONFIG_NET_BUF_DATA_POOL_SIZE=4096
diff --git a/tests/net/tcp/testcase.yaml b/tests/net/tcp/testcase.yaml
index c2df1ca45fd..7d5ccbb8fb7 100644
--- a/tests/net/tcp/testcase.yaml
+++ b/tests/net/tcp/testcase.yaml
@@ -8,3 +8,7 @@ tests:
   net.tcp.no_recv_queue:
     extra_configs:
       - CONFIG_NET_TCP_RECV_QUEUE_TIMEOUT=0
+  net.tcp.variable_buf_size:
+    extra_configs:
+      - CONFIG_NET_BUF_VARIABLE_DATA_SIZE=y
+      - CONFIG_NET_BUF_DATA_POOL_SIZE=4096