Обрыв соединения EC2 SSH; не могу переподключиться

Я успешно подключился к экземпляру EC2 следующим образом:

ssh -i .ssh/ec2docker.cer user@SOMEIP

Примерно через час использования экземпляра я ухожу и возвращаюсь еще два часа к этому:

$ packet_write_wait: Connection to xx port 22: Broken pipe

Теперь при попытке подключения вообще ничего не происходит:

OpenSSH_7.9p1, OpenSSL 1.1.1b FIPS  26 Feb 2019
debug1: Reading configuration data /etc/ssh/ssh_config
debug3: /etc/ssh/ssh_config line 52: Including file /etc/ssh/ssh_config.d/05-redhat.conf depth 0
debug1: Reading configuration data /etc/ssh/ssh_config.d/05-redhat.conf
debug2: checking match for 'final all' host xxx originally xxx
debug3: /etc/ssh/ssh_config.d/05-redhat.conf line 3: not matched 'final'
debug2: match not found
debug3: /etc/ssh/ssh_config.d/05-redhat.conf line 5: Including file /etc/crypto-policies/back-ends/openssh.config depth 1 (parse only)
debug1: Reading configuration data /etc/crypto-policies/back-ends/openssh.config
debug3: gss kex names ok: [gss-gex-sha1-,gss-group14-sha1-,gss-group1-sha1-]
debug3: kex names ok: [[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1]
debug1: configuration requests final Match pass
debug1: re-parsing configuration
debug1: Reading configuration data /etc/ssh/ssh_config
debug3: /etc/ssh/ssh_config line 52: Including file /etc/ssh/ssh_config.d/05-redhat.conf depth 0
debug1: Reading configuration data /etc/ssh/ssh_config.d/05-redhat.conf
debug2: checking match for 'final all' host xxx originally xxx
debug3: /etc/ssh/ssh_config.d/05-redhat.conf line 3: matched 'final'
debug2: match found
debug3: /etc/ssh/ssh_config.d/05-redhat.conf line 5: Including file /etc/crypto-policies/back-ends/openssh.config depth 1
debug1: Reading configuration data /etc/crypto-policies/back-ends/openssh.config
debug3: gss kex names ok: [gss-gex-sha1-,gss-group14-sha1-,gss-group1-sha1-]
debug3: kex names ok: [[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1]
debug2: resolving "xxxx" port 22
debug2: ssh_connect_direct
debug1: Connecting to xxx [xx] port 22.
debug1: Connection established.
debug1: identity file .ssh/ec2docker.cer type -1
debug1: identity file .ssh/ec2docker.cer-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_7.9

ssh не завершается или выдает ошибку. Монитор EC2 показывает, что экземпляр работает с ненулевой загрузкой ЦП (около 25%) и ненулевым чтением и записью по сети.