--- linux-4.9.37/net/ipv4/tcp_ipv4.c	2017-07-12 16:42:41.000000000 +0300
+++ linux-4.9.y/net/ipv4/tcp_ipv4.c	2021-06-07 13:01:34.000000000 +0300
@@ -2440,6 +2440,7 @@
 	net->ipv4.sysctl_tcp_ecn_fallback = 1;
 
 	net->ipv4.sysctl_tcp_base_mss = TCP_BASE_MSS;
+	net->ipv4.sysctl_tcp_min_snd_mss = TCP_MIN_SND_MSS;
 	net->ipv4.sysctl_tcp_probe_threshold = TCP_PROBE_THRESHOLD;
 	net->ipv4.sysctl_tcp_probe_interval = TCP_PROBE_INTERVAL;