Check if your servier is has
mptcpsysctl net.mptcp.enabledCheck if your server is using mptcp sudo ss -Mlnp
If you are not using it, then just disable it ...
bash
echo 'net.mptcp.enabled = 0' | sudo tee /etc/sysctl.d/90-disable-mptcp.conf sudo sysctl -w net.mptcp.enabled=0
commit 3394dd7