After upgrading to kernel-3.10.0-957.21.3.el7 on a CentOS server, I experienced connection timeout issues on Windows servers trying to access SMB shares. On the contrary, I was able to access the share using a Linux system without any problem.
Some applications set tiny SO_SNDBUF values and expect TCP to just work.
Recent patches to address CVE-2019-11478 broke them in case of losses, since re-transmits might be prevented.
To (temporarily) fix this issue, I increased
SO_SNDBUF value in
socket options = TCP_NODELAY IPTOS_LOWDELAY SO_KEEPALIVE SO_RCVBUF=65536 SO_SNDBUF=65536