diff --git a/.github/workflows/benchmarks.yml b/.github/workflows/benchmarks.yml
index 0bd37628fa5..3f7049a1a5b 100644
--- a/.github/workflows/benchmarks.yml
+++ b/.github/workflows/benchmarks.yml
@@ -85,6 +85,8 @@ jobs:
       # Run the benchmark tests
       - name: Run benchmarks
         uses: CodSpeedHQ/action@9d332c4d90b43981c3e55ae8e38e68709996240f # v4.17.0
+        env:
+          GMT_DATA_SERVER: https://opentopography.s3.sdsc.edu/gmtdata
         with:
           mode: "instrumentation"
           # 'bash -el -c' is needed to use the custom shell.
diff --git a/.github/workflows/cache_data.yaml b/.github/workflows/cache_data.yaml
index 8f83f9f4559..a0c14d874bb 100644
--- a/.github/workflows/cache_data.yaml
+++ b/.github/workflows/cache_data.yaml
@@ -70,6 +70,8 @@ jobs:
 
       # Download remote files
       - name: Download remote data
+        env:
+          GMT_DATA_SERVER: https://opentopography.s3.sdsc.edu/gmtdata
         run: |
           python -c "from pygmt.helpers.caching import cache_data; cache_data()"
 
diff --git a/.github/workflows/ci_docs.yml b/.github/workflows/ci_docs.yml
index c769ff76408..62cf388cb7d 100644
--- a/.github/workflows/ci_docs.yml
+++ b/.github/workflows/ci_docs.yml
@@ -135,6 +135,8 @@ jobs:
           python -m pip install dist/*
 
       - name: Build the HTML documentation
+        env:
+          GMT_DATA_SERVER: https://opentopography.s3.sdsc.edu/gmtdata
         run: |
           log_file="${RUNNER_TEMP}/sphinx-html.log"
           make -C doc clean html 2>&1 | tee "${log_file}"
@@ -146,6 +148,8 @@ jobs:
           exit "${exit_code}"
 
       - name: Build the PDF documentation
+        env:
+          GMT_DATA_SERVER: https://opentopography.s3.sdsc.edu/gmtdata
         run: |
           log_file="${RUNNER_TEMP}/sphinx-pdf.log"
           make -C doc pdf 2>&1 | tee "${log_file}"
diff --git a/.github/workflows/ci_doctests.yaml b/.github/workflows/ci_doctests.yaml
index c4a8d6cdbed..bda06d0491d 100644
--- a/.github/workflows/ci_doctests.yaml
+++ b/.github/workflows/ci_doctests.yaml
@@ -84,6 +84,8 @@ jobs:
 
       # Run the doctests
       - name: Run doctests
+        env:
+          GMT_DATA_SERVER: https://opentopography.s3.sdsc.edu/gmtdata
         run: |
           log_file="${RUNNER_TEMP}/pytest.log"
           make doctest PYTEST_EXTRA="-r P" 2>&1 | tee "${log_file}"
diff --git a/.github/workflows/ci_tests.yaml b/.github/workflows/ci_tests.yaml
index 9d838bfdc91..117b1229837 100644
--- a/.github/workflows/ci_tests.yaml
+++ b/.github/workflows/ci_tests.yaml
@@ -189,6 +189,8 @@ jobs:
 
       # Run the regular tests
       - name: Run tests
+        env:
+          GMT_DATA_SERVER: https://opentopography.s3.sdsc.edu/gmtdata
         run: |
           log_file="${RUNNER_TEMP}/pytest.log"
           make test PYTEST_EXTRA="-r P --reruns 2" 2>&1 | tee "${log_file}"
diff --git a/.github/workflows/ci_tests_dev.yaml b/.github/workflows/ci_tests_dev.yaml
index f185b087a27..01745d921f5 100644
--- a/.github/workflows/ci_tests_dev.yaml
+++ b/.github/workflows/ci_tests_dev.yaml
@@ -184,6 +184,7 @@ jobs:
       - name: Test with pytest
         run: make test PYTEST_EXTRA="-r P --reruns 2"
         env:
+          GMT_DATA_SERVER: https://opentopography.s3.sdsc.edu/gmtdata
           GMT_LIBRARY_PATH: ${{ runner.temp }}/gmt-install-dir/lib
 
       # Upload diff images on test failure
diff --git a/.github/workflows/ci_tests_legacy.yaml b/.github/workflows/ci_tests_legacy.yaml
index ea73fe1bef1..dabad490531 100644
--- a/.github/workflows/ci_tests_legacy.yaml
+++ b/.github/workflows/ci_tests_legacy.yaml
@@ -95,4 +95,6 @@ jobs:
 
       # Run the tests but skip images
       - name: Run tests
+        env:
+          GMT_DATA_SERVER: https://opentopography.s3.sdsc.edu/gmtdata
         run: make test_no_images PYTEST_EXTRA="-r P"
diff --git a/examples/tutorials/advanced/draping_on_3d_surface.py b/examples/tutorials/advanced/draping_on_3d_surface.py
index 4479df5a06d..db5228f94ca 100644
--- a/examples/tutorials/advanced/draping_on_3d_surface.py
+++ b/examples/tutorials/advanced/draping_on_3d_surface.py
@@ -99,7 +99,9 @@
 # The original image is available on Wikimedia Commons at
 # https://commons.wikimedia.org/wiki/File:Flag_of_Europe.svg
 # but we use a cached version on the GMT data server.
-url_to_image = "https://oceania.generic-mapping-tools.org/cache/euflag.png"
+url_to_image = (
+    "https://github.com/GenericMappingTools/gmtserver-admin/raw/master/cache/euflag.png"
+)
 with rasterio.open(url_to_image) as dataset:
     data = dataset.read()
     drape_grid = xr.DataArray(data, dims=("band", "y", "x"))
diff --git a/pygmt/tests/test_datatypes_dataset.py b/pygmt/tests/test_datatypes_dataset.py
index f170e22d7bf..1e6ab838d9c 100644
--- a/pygmt/tests/test_datatypes_dataset.py
+++ b/pygmt/tests/test_datatypes_dataset.py
@@ -156,25 +156,17 @@ def test_dataset_to_strings_with_none_values():
 
     See the bug report at https://github.com/GenericMappingTools/pygmt/issues/3170.
     """
-    # Sometimes, the test may fail in CI due to intermittent internet connection issue.
-    # Catch the FileNotFoundError exception so that we can focus on the bug.
     tiles = ["@N30E060.earth_age_01m_g.nc", "@N30E090.earth_age_01m_g.nc"]
-    try:
-        paths = which(fname=tiles, download="auto")
-        assert len(paths) == 2
 
-        # 'paths' may contain an empty string or not, depending on if tiles are cached.
-        if "" not in paths:  # Contains two valid paths.
-            # Delete the cached tiles and try again.
-            for path in paths:
-                Path(path).unlink()
-            with pytest.warns(expected_warning=RuntimeWarning) as record:  # noqa: PT031
-                try:
-                    paths = which(fname=tiles, download="auto")
-                    assert len(record) == 1
-                    assert len(paths) == 2
-                    assert "" in paths
-                except FileNotFoundError:
-                    pass
-    except FileNotFoundError:
-        pass
+    paths = which(fname=tiles, download="auto")
+    assert len(paths) == 2
+    # 'paths' may contain an empty string or not, depending on if the tiles are cached.
+    if "" not in paths:  # Contains two valid paths.
+        # Delete the cached tiles and try again.
+        for path in paths:
+            Path(path).unlink()
+        with pytest.warns(expected_warning=RuntimeWarning) as record:
+            paths = which(fname=tiles, download="auto")
+        assert len(record) == 1
+        assert len(paths) == 2
+        assert "" in paths
diff --git a/pygmt/tests/test_which.py b/pygmt/tests/test_which.py
index 40f6eb31ccc..fd07b32b94b 100644
--- a/pygmt/tests/test_which.py
+++ b/pygmt/tests/test_which.py
@@ -68,10 +68,7 @@ def test_which_nonascii_path(monkeypatch):
             # Start a new session
             begin()
             # GMT should download the remote file under the new home directory.
-            try:
-                fname = which(fname="@static_earth_relief.nc", download="cache")
-            except FileNotFoundError:
-                pytest.skip("Failed to download the file, skipping the test.")
+            fname = which(fname="@static_earth_relief.nc", download="cache")
             assert fname.startswith(fakehome)
             assert fname.endswith("static_earth_relief.nc")
             end()