JVB crashing without any obviuous reason

Hi…we have deployed jitsi for online school classes. Everythings look good, but intermittently the jvb crashes and log shows lot of these entries:

Sctp send error: : Resource temporarily unavailable

2020-05-08 09:55:22.366 INFO: [2512] [confId=ba7074a1b5cd8ecf gid=ffcf17 stats_id=Enrico-0Bl conf_name=mkvviv10d080520 ufrag=d840t1e7p6h2gi epId=e24b55f4 local_ufrag=d840t1e7p6h2gi] ConnectivityCheckClient.processTimeout#857: timeout for pair: 164.52.199.214:10000/udp/host -> 49.32.33.12:55176/udp/prflx (stream-e24b55f4.RTP), failing.

Sctp send error: : Resource temporarily unavailable

Sctp send error: : Resource temporarily unavailable

Sctp send error: : Resource temporarily unavailable

Sctp send error: : Resource temporarily unavailable

Sctp send error: : Resource temporarily unavailable

Sctp send error: : Resource temporarily unavailable

wherein prosody shows this error:

May 08 06:40:04 localhost:tls error Error creating contexts for s2sin: error loading private key (system lib)

May 08 09:20:46 portmanager error Failed to open server port 5347 on ::1, Cannot assign requested address

May 08 09:20:46 portmanager error Error binding encrypted port for https: No certificate present in SSL/TLS configuration for https port 5281

May 08 09:20:46 portmanager error Error binding encrypted port for https: No certificate present in SSL/TLS configuration for https port 5281

May 08 09:20:46 certmanager error SSL/TLS: Failed to load ‘/etc/prosody/certs/localhost.key’: Check that the permissions allow Prosody to read this file. (for localhost)

May 08 09:20:46 localhost:tls error Error creating context for c2s: error loading private key (Permission denied)

May 08 09:20:46 certmanager error SSL/TLS: Failed to load ‘/etc/prosody/certs/localhost.key’: Previous error (see logs), or other system error. (for localhost)

May 08 09:20:46 localhost:tls error Error creating contexts for s2sout: error loading private key (system lib)

May 08 09:20:46 certmanager error SSL/TLS: Failed to load ‘/etc/prosody/certs/localhost.key’: Previous error (see logs), or other system error. (for localhost)

May 08 09:20:46 localhost:tls error Error creating contexts for s2sin: error loading private key (system lib)

Can anybody help to fix these ?