Why can postgres streaming replicas crash?

Question

PostgreSQL

Everything started to fall, 10 pieces, together the day before yesterday, without any previously visible reasons, strictly at a certain time, first at 0 UTC, today at exactly 0 hours EST
OS ubuntu 16.04, version PG 9.5 replica logs
2019-04-13 00: 00:03.370 EST [2267] LOG: 00000: invalid record length at 1BCA/DA0E0258 2019-04-13 00:00:03.370 EST [2267] LOCATION: ReadRecord, xlog.c:4012
2019-04-13 00:00: 03.370 EST [14961] FATAL: 57P01: terminating walreceiver process due to administrator command 2019-04-13 00:00:03.370 EST [14961] LOCATION: ProcessWalRcvInterrupts, walreceiver.c:
167 [2267] LOG: 00000: invalid record length at 1BCA/DA0E0258
2019-04-13 00:00:03.370 EST [2267] LOCATION: ReadRecord, xlog.c:4012
2019-04-13 00:00: 03.370 EST [2267] LOG: 00000: invalid record length at 1BCA/
DA0E0258 04-13 00:00:03.370 EST [2267] LOG: 00000: invalid record length at 1BCA/DA0E0258
2019-04-13 00:00:03.370 EST [2267] LOCATION: ReadRecord, xlog.c:
4012 this time - nothing at all!
2019-04-12 23:59:49.854 EST [49236] [email protected] LOG: 08006: could not receive data from client: Connection reset by peer
2019-04-12 23:59:49.854 EST [49236] [email protected] LOCATION : pq_recvbuf, pqcomm.c:919
2019-04-13 00:00:09.589 EST [49559] [email protected] LOG: 08006: could not receive data from client: Connection reset by peer
2019-04-13 00:00:09.589 EST [49559] [email protected] LOCATION: pq_recvbuf, pqcomm.c:
919 data from client: Connection reset by peer
2019-04-13 00:00:09.589 EST [49561] [email protected] LOCATION: pq_recvbuf, pqcomm.c:919
2019-04-13 00:00:09.589 EST [49556] [email protected] aaa LOG: 08006: could not receive data from client: Connection reset by peer
now restored 2 replicas out of 10, waiting for 0 est hours

postgres=# select * from pg_stat_replication;

pid | usesysid | usename | application_name | client_addr | client_hostname | client_port | backend_start | backend_xmin | state | sent_location | write_location | flush_location | replay_location | sync_priority | sync_state -------+----------+----------+------------------+----------------+-----------------+-------------+-------------------------------+--------------+-----------+---------------+----------------+----------------+-----------------+---------------+------------

92078 | 10 | postgres | walreceiver | 18.72.2.14 | | 2184 | 2019-04-13 05:59:55.361197-05 | | streaming | 1BD6/63740D68 | 1BD6/63740D68 | 1BD6/63740D68 | 1BD6/6373DE78 | 0 | async

91982 | 10 | postgres | walreceiver | 31.22.2.8 | | 31620 | 2019-04-13 05:59:38.198516-05 | 486133549 | streaming | 1BD6/63740D68 | 1BD6/63740D68 | 1BD6/63740D68 | 1BD6/6373DE78 | 0 | async

(2 rows)