diff --git a/contrib/seeds/test-seeds.sh b/contrib/seeds/test-seeds.sh
index 29eaae0242..bc89ff2759 100755
--- a/contrib/seeds/test-seeds.sh
+++ b/contrib/seeds/test-seeds.sh
@@ -1,130 +1,133 @@
 #!/usr/bin/env bash
 # Copyright (c) 2019 The Bitcoin developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 export LC_ALL=C
 
 set -u
 
 TOPLEVEL=$(git rev-parse --show-toplevel)
 DEFAULT_BUILD_DIR="${TOPLEVEL}/build"
+DEFAULT_RPC_PORT=18832
 
 help_message() {
   echo "Test connecting to seed nodes. Outputs the seeds that were successfully connected to."
   echo ""
   echo "Example usages:"
   echo "Mainnet: $0 < nodes_main.txt"
   echo "Testnet: $0 --testnet < nodes_test.txt"
   echo ""
   echo "Options:"
   echo "-t, --testnet         Connect to testnet seeds (mainnet is default)."
   echo "-h, --help            Display this help message."
   echo ""
   echo "Environment Variables:"
   echo "BUILD_DIR             Default: ${DEFAULT_BUILD_DIR}"
+  echo "RPC_PORT              Default: ${DEFAULT_RPC_PORT}"
   exit 0
 }
 
 : "${BUILD_DIR:=${DEFAULT_BUILD_DIR}}"
 OPTION_TESTNET=""
 
 # Parse command line arguments
 while [[ $# -gt 0 ]]; do
 case $1 in
   -t|--testnet)
     OPTION_TESTNET="--testnet"
     shift # shift past argument
     ;;
   -h|--help)
     help_message
     shift # shift past argument
     ;;
   *)
     echo "Unknown argument: $1"
     help_message
     shift # shift past argument
     ;;
 esac
 done
 
 BITCOIND="${BUILD_DIR}/src/bitcoind"
 BITCOIN_CLI="${BUILD_DIR}/src/bitcoin-cli"
 if [ ! -x "${BITCOIND}" ]; then
   echo "${BITCOIND} does not exist or has incorrect permissions."
   exit 10
 fi
 if [ ! -x "${BITCOIN_CLI}" ]; then
   echo "${BITCOIN_CLI} does not exist or has incorrect permissions."
   exit 11
 fi
 
 TEMP_DATADIR=$(mktemp -d)
-BITCOIND="${BITCOIND} -datadir=${TEMP_DATADIR} ${OPTION_TESTNET} -rpcport=18832 -connect=0 -daemon"
-BITCOIN_CLI="${BITCOIN_CLI} -datadir=${TEMP_DATADIR} ${OPTION_TESTNET} -rpcport=18832"
+: "${RPC_PORT:=${DEFAULT_RPC_PORT}}"
+BITCOIND="${BITCOIND} -datadir=${TEMP_DATADIR} ${OPTION_TESTNET} -rpcport=${RPC_PORT} -connect=0 -daemon"
+BITCOIN_CLI="${BITCOIN_CLI} -datadir=${TEMP_DATADIR} ${OPTION_TESTNET} -rpcport=${RPC_PORT}"
 
 >&2 echo "Spinning up bitcoind..."
 ${BITCOIND} || {
   echo "Error starting bitcoind. Stopping script."
   exit 12
 }
 cleanup() {
   # Cleanup background processes spawned by this script.
   >&2 echo "Cleaning up bitcoin daemon..."
   ${BITCOIN_CLI} stop
   rm -rf "${TEMP_DATADIR}"
 }
 trap "cleanup" EXIT
 
 # Short sleep to make sure the RPC server is available
 sleep 0.1
 # Wait until bitcoind is fully spun up
 WARMUP_TIMEOUT=60
 for _ in $(seq 1 ${WARMUP_TIMEOUT}); do
   ${BITCOIN_CLI} getconnectioncount &> /dev/null
   RPC_READY=$?
   if [ "${RPC_READY}" -ne 0 ]; then
     >&2 printf "."
     sleep 1
   else
     break
   fi
 done
 >&2 echo ""
 
 if [ "${RPC_READY}" -ne 0 ]; then
   >&2 echo "RPC was not ready after ${WARMUP_TIMEOUT} seconds."
   exit 20
 fi
 
 while read -r SEED; do
   >&2 echo "Testing seed '${SEED}'..."
 
   # Immediately connect to the seed peer
   ${BITCOIN_CLI} addnode "${SEED}" onetry
 
   # Fetch peer's connection status
   CONNECTION_COUNT=$(${BITCOIN_CLI} getconnectioncount)
   if [ "${CONNECTION_COUNT}" -eq 1 ]; then
     # Cleanup peer connection
     ${BITCOIN_CLI} disconnectnode "${SEED}"
 
     # Wait for peer to be disconnected
     CONNECTED_TIMEOUT=5
     for _ in $(seq 1 ${CONNECTED_TIMEOUT}); do
       CONNECTION_COUNT=$(${BITCOIN_CLI} getconnectioncount)
       if [ "${CONNECTION_COUNT}" -eq 0 ]; then
         break
       fi
       sleep 0.1
     done
     if [ "${CONNECTION_COUNT}" -ne 0 ]; then
       >&2 echo "Seed failed to disconnect. Something else could be wrong (check logs)."
       exit 30
     fi
 
     echo "${SEED}"
   else
     >&2 echo "Failed to connect to '${SEED}'"
   fi
 done
diff --git a/contrib/teamcity/build-configurations.sh b/contrib/teamcity/build-configurations.sh
index 306afbc3a7..44c922fb27 100755
--- a/contrib/teamcity/build-configurations.sh
+++ b/contrib/teamcity/build-configurations.sh
@@ -1,265 +1,267 @@
 #!/usr/bin/env bash
 
 export LC_ALL=C.UTF-8
 
 set -euxo pipefail
 
 : "${ABC_BUILD_NAME:=""}"
 if [ -z "$ABC_BUILD_NAME" ]; then
   echo "Error: Environment variable ABC_BUILD_NAME must be set"
   exit 1
 fi
 
 echo "Running build configuration '${ABC_BUILD_NAME}'..."
 
 TOPLEVEL=$(git rev-parse --show-toplevel)
 export TOPLEVEL
 
 setup() {
   : "${BUILD_DIR:=${TOPLEVEL}/build}"
   mkdir -p "${BUILD_DIR}"
   BUILD_DIR=$(cd "${BUILD_DIR}"; pwd)
   export BUILD_DIR
 
   cd "${BUILD_DIR}"
 
   # Determine the number of build threads
   THREADS=$(nproc || sysctl -n hw.ncpu)
   export THREADS
 
   # Base directories for sanitizer related files 
   SAN_SUPP_DIR="${TOPLEVEL}/test/sanitizer_suppressions"
   SAN_LOG_DIR="/tmp/sanitizer_logs"
 
   # Create the log directory if it doesn't exist and clear it
   mkdir -p "${SAN_LOG_DIR}"
   rm -rf "${SAN_LOG_DIR:?}"/*
 
   # Sanitizers options, not used if sanitizers are not enabled
   export ASAN_OPTIONS="malloc_context_size=0:log_path=${SAN_LOG_DIR}/asan.log"
   export LSAN_OPTIONS="suppressions=${SAN_SUPP_DIR}/lsan:log_path=${SAN_LOG_DIR}/lsan.log"
   export TSAN_OPTIONS="suppressions=${SAN_SUPP_DIR}/tsan:log_path=${SAN_LOG_DIR}/tsan.log"
   export UBSAN_OPTIONS="suppressions=${SAN_SUPP_DIR}/ubsan:print_stacktrace=1:halt_on_error=1:log_path=${SAN_LOG_DIR}/ubsan.log"
 
   # Unit test logger parameters
   UNIT_TESTS_JUNIT_LOG_LEVEL=message
 }
 
 run_test_bitcoin() {
   # Usage: run_test_bitcoin "Context as string" [arguments...]
   ninja test_bitcoin
 
   TEST_BITCOIN_JUNIT="junit_results_unit_tests${1:+_${1// /_}}.xml"
   TEST_BITCOIN_SUITE_NAME="Bitcoin ABC unit tests${1:+ $1}"
 
   ./src/test/test_bitcoin \
     --logger=HRF:JUNIT,${UNIT_TESTS_JUNIT_LOG_LEVEL},${TEST_BITCOIN_JUNIT} \
     -- \
     -testsuitename="${TEST_BITCOIN_SUITE_NAME}" \
     "${@:2}"
 }
 
 # Facility to print out sanitizer log outputs to the build log console
 print_sanitizers_log() {
   for log in "${SAN_LOG_DIR}"/*.log.*
   do
     echo "*** Output of ${log} ***"
     cat "${log}"
   done
 }
 trap "print_sanitizers_log" ERR
 
 CI_SCRIPTS_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
 setup
 
 case "$ABC_BUILD_NAME" in
   build-asan)
     # Build with the address sanitizer, then run unit tests and functional tests.
     CMAKE_FLAGS=(
       "-DCMAKE_CXX_FLAGS=-DARENA_DEBUG"
       "-DCMAKE_BUILD_TYPE=Debug"
       # ASAN does not support assembly code: https://github.com/google/sanitizers/issues/192
       # This will trigger a segfault if the SSE4 implementation is selected for SHA256.
       # Disabling the assembly works around the issue.
       "-DCRYPTO_USE_ASM=OFF"
       "-DENABLE_SANITIZERS=address"
       "-DCCACHE=OFF"
       "-DCMAKE_C_COMPILER=clang"
       "-DCMAKE_CXX_COMPILER=clang++"
     )
     CMAKE_FLAGS="${CMAKE_FLAGS[*]}" "${CI_SCRIPTS_DIR}"/build_cmake.sh
 
     run_test_bitcoin "with address sanitizer"
 
     # Libs and utils tests
     ninja \
       check-bitcoin-qt \
       check-bitcoin-seeder \
       check-bitcoin-util \
 
     ninja check-functional
     ;;
 
   build-ubsan)
     # Build with the undefined sanitizer, then run unit tests and functional tests.
     CMAKE_FLAGS=(
       "-DCMAKE_BUILD_TYPE=Debug"
       "-DENABLE_SANITIZERS=undefined"
       "-DCCACHE=OFF"
       "-DCMAKE_C_COMPILER=clang"
       "-DCMAKE_CXX_COMPILER=clang++"
     )
     CMAKE_FLAGS="${CMAKE_FLAGS[*]}" "${CI_SCRIPTS_DIR}"/build_cmake.sh
 
     run_test_bitcoin "with undefined sanitizer"
 
     # Libs and utils tests
     ninja \
       check-bitcoin-qt \
       check-bitcoin-seeder \
       check-bitcoin-util \
 
     ninja check-functional
     ;;
 
   build-tsan)
     # Build with the thread sanitizer, then run unit tests and functional tests.
     CMAKE_FLAGS=(
       "-DCMAKE_BUILD_TYPE=Debug"
       "-DENABLE_SANITIZERS=thread"
       "-DCCACHE=OFF"
       "-DCMAKE_C_COMPILER=clang"
       "-DCMAKE_CXX_COMPILER=clang++"
     )
     CMAKE_FLAGS="${CMAKE_FLAGS[*]}" "${CI_SCRIPTS_DIR}"/build_cmake.sh
 
     run_test_bitcoin "with thread sanitizer"
 
     # Libs and utils tests
     ninja \
       check-bitcoin-qt \
       check-bitcoin-seeder \
       check-bitcoin-util \
 
     ninja check-functional
     ;;
 
   build-diff)
     # Build, run unit tests and functional tests.
     CMAKE_FLAGS=(
       "-DSECP256K1_ENABLE_MODULE_ECDH=ON"
       "-DSECP256K1_ENABLE_JNI=ON"
     )
     CMAKE_FLAGS="${CMAKE_FLAGS[*]}" "${CI_SCRIPTS_DIR}"/build_cmake.sh
 
     # Unit tests
     run_test_bitcoin
     run_test_bitcoin "with next upgrade activated" -phononactivationtime=1575158400
 
     # Libs and tools tests
     ninja \
       check-bitcoin-qt \
       check-bitcoin-seeder \
       check-bitcoin-util \
       check-devtools \
       check-leveldb \
       check-rpcauth \
       check-secp256k1 \
       check-univalue \
 
     # Functional tests
     ninja check-functional
     ninja check-functional-upgrade-activated
     ;;
 
   build-master)
     # Build, run unit tests and extended functional tests.
     CMAKE_FLAGS=(
       "-DSECP256K1_ENABLE_MODULE_ECDH=ON"
       "-DSECP256K1_ENABLE_JNI=ON"
     )
     CMAKE_FLAGS="${CMAKE_FLAGS[*]}" "${CI_SCRIPTS_DIR}"/build_cmake.sh
 
     # Unit tests
     run_test_bitcoin
     run_test_bitcoin "with next upgrade activated" -phononactivationtime=1575158400
 
     # Libs and tools tests
     ninja \
       check-bitcoin-qt \
       check-bitcoin-seeder \
       check-bitcoin-util \
       check-devtools \
       check-leveldb \
       check-rpcauth \
       check-secp256k1 \
       check-univalue \
 
     # Functional tests
     ninja check-functional-extended
     ninja check-functional-upgrade-activated-extended
     ;;
 
   build-without-wallet)
     # Build without wallet and run the unit tests.
     CMAKE_FLAGS=(
       "-DBUILD_BITCOIN_WALLET=OFF"
     )
     CMAKE_FLAGS="${CMAKE_FLAGS[*]}" "${CI_SCRIPTS_DIR}"/build_cmake.sh
 
     ninja check-bitcoin-qt
     ninja check-functional
 
     run_test_bitcoin "without wallet"
     ;;
 
   build-ibd)
     "${CI_SCRIPTS_DIR}"/build_cmake.sh
     "${CI_SCRIPTS_DIR}"/ibd.sh -disablewallet -debug=net
     ;;
 
   build-ibd-no-assumevalid-checkpoint)
     "${CI_SCRIPTS_DIR}"/build_cmake.sh
     "${CI_SCRIPTS_DIR}"/ibd.sh -disablewallet -assumevalid=0 -checkpoints=0 -debug=net
     ;;
 
   build-werror)
     # Build with variable-length-array and thread-safety-analysis treated as errors
     CMAKE_FLAGS=(
       "-DENABLE_WERROR=ON"
       "-DCMAKE_C_COMPILER=clang"
       "-DCMAKE_CXX_COMPILER=clang++"
     )
     CMAKE_FLAGS="${CMAKE_FLAGS[*]}" "${CI_SCRIPTS_DIR}"/build_cmake.sh
     ;;
 
   build-autotools)
     # Ensure that the build using autotools is not broken
     "${CI_SCRIPTS_DIR}"/build_autotools.sh
     make -j "${THREADS}" check
     ;;
 
   build-bench)
     # Build and run the benchmarks.
     CMAKE_FLAGS=(
       "-DBUILD_BITCOIN_WALLET=ON"
       "-DSECP256K1_ENABLE_MODULE_ECDH=ON"
       "-DSECP256K1_ENABLE_MODULE_MULTISET=ON"
       "-DSECP256K1_ENABLE_MODULE_RECOVERY=ON"
     )
     CMAKE_FLAGS="${CMAKE_FLAGS[*]}" "${CI_SCRIPTS_DIR}"/build_cmake.sh
     ninja bench-bitcoin
     ninja bench-secp256k1
     ;;
 
   check-seeds)
     "${CI_SCRIPTS_DIR}"/build_cmake.sh
-    "${CI_SCRIPTS_DIR}"/check-seeds.sh main 80
-    "${CI_SCRIPTS_DIR}"/check-seeds.sh test 70
+    # Run on different ports to avoid a race where the rpc port used in the
+    # first run may not be closed in time for the second to start.
+    RPC_PORT=18832 "${CI_SCRIPTS_DIR}"/check-seeds.sh main 80
+    RPC_PORT=18833 "${CI_SCRIPTS_DIR}"/check-seeds.sh test 70
     ;;
 
   *)
     echo "Error: Invalid build name '${ABC_BUILD_NAME}'"
     exit 2
     ;;
 esac