This is the log of a router trying to connext to the VPN:
Thu Sep 22 17:29:29 2022 daemon.err openvpn(client_alfa)[8732]: TLS Error: TLS key negotiation failed to occur within 60 seconds (check your network connectivity)
Thu Sep 22 17:29:29 2022 daemon.err openvpn(client_alfa)[8732]: TLS Error: TLS handshake failed
Thu Sep 22 17:29:29 2022 daemon.notice openvpn(client_alfa)[8732]: TCP/UDP: Closing socket
Thu Sep 22 17:29:29 2022 daemon.notice openvpn(client_alfa)[8732]: SIGUSR1[soft,tls-error] received, process restarting
Thu Sep 22 17:29:29 2022 daemon.notice openvpn(client_alfa)[8732]: Restart pause, 5 second(s)
Thu Sep 22 17:29:34 2022 daemon.warn openvpn(client_alfa)[8732]: WARNING: No server certificate verification method has been enabled. See http://openvpn.net/howto.html#mitm for more info.
Thu Sep 22 17:29:34 2022 daemon.notice openvpn(client_alfa)[8732]: Re-using SSL/TLS context
Thu Sep 22 17:29:34 2022 daemon.notice openvpn(client_alfa)[8732]: LZO compression initializing
Thu Sep 22 17:29:34 2022 daemon.notice openvpn(client_alfa)[8732]: Control Channel MTU parms [ L:1622 D:1212 EF:38 EB:0 ET:0 EL:3 ]
Thu Sep 22 17:29:34 2022 daemon.notice openvpn(client_alfa)[8732]: Data Channel MTU parms [ L:1622 D:1450 EF:122 EB:406 ET:0 EL:3 ]
Thu Sep 22 17:29:34 2022 daemon.notice openvpn(client_alfa)[8732]: Local Options String (VER=V4): 'V4,dev-type tun,link-mtu 1558,tun-mtu 1500,proto UDPv4,comp-lzo,cipher AES-256-CBC,auth SHA1,keysize 256,key-method 2,tls-client'
Thu Sep 22 17:29:34 2022 daemon.notice openvpn(client_alfa)[8732]: Expected Remote Options String (VER=V4): 'V4,dev-type tun,link-mtu 1558,tun-mtu 1500,proto UDPv4,comp-lzo,cipher AES-256-CBC,auth SHA1,keysize 256,key-method 2,tls-server'
Thu Sep 22 17:29:34 2022 daemon.notice openvpn(client_alfa)[8732]: TCP/UDP: Preserving recently used remote address: [AF_INET]89.34.236.90:1194
Thu Sep 22 17:29:34 2022 daemon.notice openvpn(client_alfa)[8732]: Socket Buffers: R=[8388608->8388608] S=[8388608->8388608]
Thu Sep 22 17:29:34 2022 daemon.notice openvpn(client_alfa)[8732]: UDP link local: (not bound)
Thu Sep 22 17:29:34 2022 daemon.notice openvpn(client_alfa)[8732]: UDP link remote: [AF_INET]89.34.236.90:1194
Thu Sep 22 17:29:34 2022 daemon.notice openvpn(client_alfa)[8732]: TLS: Initial packet from [AF_INET]89.34.236.90:1194, sid=ff46edf9 22aa69cb
Thu Sep 22 17:29:34 2022 daemon.notice openvpn(client_alfa)[8732]: VERIFY OK: depth=1, C=IT, ST=VA, L=Varese, O=*************, OU=MyOrganizationalUnit, CN=*************CA, name=server, emailAddress=*************
Thu Sep 22 17:29:34 2022 daemon.notice openvpn(client_alfa)[8732]: VERIFY OK: depth=0, C=IT, ST=VA, L=Varese, O=*************, OU=MyOrganizationalUnit, CN=server, name=server, emailAddress=*************
https://community.teltonika-networks.com/?qa=blob&qa_blobid=9031169556095787425
https://community.teltonika-networks.com/?qa=blob&qa_blobid=17664010032941447776
Here the link of the logs. The problem occured around 00:50-01:05AM on 21 september 2022.
Thank you very much