There was a serious winter storm and the whole mobile nerwork was down for two days. That happened exactly at the same time I changed the remote router's configuration and lost totally the connection. Now I can connect again to the remote router (thru hhtp and hhtps) but the IPSEC still doesn't work. Now the configuration has done according to this document:
https://community.teltonika-networks.com/?qa=blob&qa_blobid=2523811953889951933 and there is no "remote vpn endpoint" or static routes at the server (mobile) side. There is a sample of the client router's log. Same errors occur at the server side.
Sun Jan 6 12:23:51 2019 daemon.info syslog: 16[ENC] generating QUICK_MODE request 1591028077 [ HASH SA No KE ID ID ]
Sun Jan 6 12:23:51 2019 daemon.info syslog: 16[NET] sending packet: from 78.XX.XXX.XXX[500] to 188.XX.XX.XX[500] (372 bytes)
Sun Jan 6 12:23:51 2019 daemon.info syslog: 05[NET] received packet: from 188.XX.XX.XX[500] to 78.XX.XXX.XXX[500] (372 bytes)
Sun Jan 6 12:23:51 2019 daemon.info syslog: 05[ENC] parsed QUICK_MODE response 1591028077 [ HASH SA No KE ID ID ]
Sun Jan 6 12:23:52 2019 user.info Messaged[4735]: Start from new event "Output" "Digital relay output off"
Sun Jan 6 12:23:52 2019 user.info Messaged[4751]: Start from new event "Output" "Digital OC output off"
Sun Jan 6 12:23:52 2019 cron.info crond[4761]: crond (busybox 1.28.3) started, log level 5
Sun Jan 6 12:23:53 2019 daemon.info syslog: 05[KNL] received netlink error: Network is unreachable (128)
Sun Jan 6 12:23:53 2019 daemon.info syslog: 05[KNL] unable to install source route for 192.168.0.1