test: Fix intermittent issue in wallet_assumeutxo.py

diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
index d246a744..3a6346a3 100644
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -721,6 +721,16 @@ def find_vout_for_address(node, txid, addr):
     raise RuntimeError("Vout not found for address: txid=%s, addr=%s" % (txid, addr))
 
 
+def dumb_sync_blocks(*, src, dst, height=None):
+    """Sync blocks between `src` and `dst` nodes via RPC submitblock up to height."""
+    height = height or src.getblockcount()
+    for i in range(dst.getblockcount() + 1, height + 1):
+        block_hash = src.getblockhash(i)
+        block = src.getblock(blockhash=block_hash, verbose=0)
+        dst.submitblock(block)
+    assert_equal(dst.getblockcount(), height)
+
+
 def sync_txindex(test_framework, node):
     test_framework.log.debug("Waiting for node txindex to sync")
     sync_start = int(time.time())
diff --git a/test/functional/wallet_assumeutxo.py b/test/functional/wallet_assumeutxo.py
index 926d4b16..355fc32b 100755
--- a/test/functional/wallet_assumeutxo.py
+++ b/test/functional/wallet_assumeutxo.py
@@ -12,8 +12,8 @@ from test_framework.messages import COIN
 from test_framework.util import (
     assert_equal,
     assert_greater_than,
-    assert_greater_than_or_equal,
     assert_raises_rpc_error,
+    dumb_sync_blocks,
     ensure_for,
 )
 from test_framework.wallet import MiniWallet
@@ -42,8 +42,8 @@ class AssumeutxoTest(BitcoinTestFramework):
     def setup_network(self):
         """Start with the nodes disconnected so that one can generate a snapshot
         including blocks the other hasn't yet seen."""
-        self.add_nodes(4)
-        self.start_nodes(extra_args=self.extra_args)
+        self.add_nodes(self.num_nodes, self.extra_args)
+        self.start_nodes()
 
     def import_descriptor(self, node, wallet_name, key, timestamp):
         import_request = [{"desc": descsum_create("pkh(" + key.pubkey + ")"),
@@ -227,32 +227,18 @@ class AssumeutxoTest(BitcoinTestFramework):
 
         PAUSE_HEIGHT = FINAL_HEIGHT - 40
 
-        self.log.info("Restarting node to stop at height %d", PAUSE_HEIGHT)
-        self.restart_node(1, extra_args=[
-            f"-stopatheight={PAUSE_HEIGHT}", *self.extra_args[1]])
+        self.log.info(f"Unload wallets and sync node up to height {PAUSE_HEIGHT}")
+        n1.unloadwallet("w")
+        n1.unloadwallet(wallet_name)
+        dumb_sync_blocks(src=n0, dst=n1, height=PAUSE_HEIGHT)
 
-        # Finally connect the nodes and let them sync.
-        #
-        # Set `wait_for_connect=False` to avoid a race between performing connection
-        # assertions and the -stopatheight tripping.
-        self.connect_nodes(0, 1, wait_for_connect=False)
-
-        n1.wait_until_stopped(timeout=5)
-
-        self.log.info(
-            "Restarted node before snapshot validation completed, reloading...")
-        self.restart_node(1, extra_args=self.extra_args[1])
-
-        self.log.info("Verify node state after restart during background sync")
+        self.log.info("Verify node state during background sync")
         # Verify there are still two chainstates (background validation not complete)
         chainstates = n1.getchainstates()['chainstates']
         assert_equal(len(chainstates), 2)
         # The background chainstate should still be at START_HEIGHT
         assert_equal(chainstates[0]['blocks'], START_HEIGHT)
-        # The snapshot chainstate should be at least PAUSE_HEIGHT. It may be
-        # higher because stopatheight may allow additional blocks to be
-        # processed during shutdown (per stopatheight documentation).
-        assert_greater_than_or_equal(chainstates[1]['blocks'], PAUSE_HEIGHT)
+        assert_equal(chainstates[1]["blocks"], PAUSE_HEIGHT)
 
         # After restart, wallets that existed before cannot be loaded because
         # the wallet loading code checks if required blocks are available for