I set up small test Mesosphere cluster according to this guide https://dcos.io/docs/1.8/administration/installing/custom/cli/ everything went smoothly. There are only 3 nodes in cluster, one for bootstrap, one master(10.7.1.12) and one agent(10.7.1.13).
But after rebooting machine with agent node, it is no longer visible by master node 
.
In /var/log/mesos/mesos-agent.log last input has timestamp before reboot.
I was trying all steps from https://dcos.io/docs/1.8/administration/installing/custom/troubleshooting/ but nothing changed.
Here are the logs from master after agent disconnection (sudo journalctl -u dcos-mesos-master)
lut 06 15:48:14 arangodb2.test1.fgtsa.com mesos-master[2661]: I0206 15:48:14.556001 2671 master.cpp:1245] Agent d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-S0 at slave(1)@10.7.1.13:5051 (10.7.1.13) disconnected
lut 06 15:48:14 arangodb2.test1.fgtsa.com mesos-master[2661]: I0206 15:48:14.556089 2671 master.cpp:2784] Disconnecting agent d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-S0 at slave(1)@10.7.1.13:5051 (10.7.1.13)
lut 06 15:48:14 arangodb2.test1.fgtsa.com mesos-master[2661]: I0206 15:48:14.556170 2671 master.cpp:2803] Deactivating agent d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-S0 at slave(1)@10.7.1.13:5051 (10.7.1.13)
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: W0206 15:53:16.926198 2670 master.cpp:5334] Shutting down agent d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-S0 at slave(1)@10.7.1.13:5051 (10.7.1.13) with message 'health check timed out'
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: I0206 15:53:16.926230 2670 master.cpp:6617] Removing agent d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-S0 at slave(1)@10.7.1.13:5051 (10.7.1.13): health check timed out
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: I0206 15:53:16.926507 2670 master.cpp:6910] Removing task 93f4b075-1338-4a84-afd6-6932cfe44c30 with resources mem(arangodb31, arangodb3):2048; cpus(arangodb31, arangodb3):0.25; disk(arangodb31, arangodb3)[AGENCY_991972e5-2d83-4710-ba3c-de8cf02303ab:myPersistentVolume]:2048; ports(arangodb31, arangodb3):[1026-1026] of framework d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-0004 on agent d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-S0 at slave(1)@10.7.1.13:5051 (10.7.1.13)
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: I0206 15:53:16.926695 2670 master.cpp:6910] Removing task 644b59eb-fb20-43fd-a7c1-b1d9406cbfcb with resources mem(arangodb3, arangodb3):2048; cpus(arangodb3, arangodb3):0.25; disk(arangodb3, arangodb3)[AGENCY_0c76702f-ae8b-423c-83a8-1b6e2af8b723:myPersistentVolume]:2048; ports(arangodb3, arangodb3):[1025-1025] of framework d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-0002 on agent d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-S0 at slave(1)@10.7.1.13:5051 (10.7.1.13)
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: I0206 15:53:16.928460 2670 master.cpp:6736] Removed agent d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-S0 (10.7.1.13): health check timed out
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: I0206 15:53:16.928472 2670 master.cpp:5197] Sending status update TASK_LOST for task 93f4b075-1338-4a84-afd6-6932cfe44c30 of framework d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-0004 'Slave 10.7.1.13 removed: health check timed out'
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: W0206 15:53:16.928486 2670 master.hpp:2113] Master attempted to send message to disconnected framework d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-0004 (arangodb3-1) at scheduler-f4f3a3f0-2261-4aaf-9390-81f4b1cc6d20@10.7.1.13:25366
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: I0206 15:53:16.928611 2670 master.cpp:5197] Sending status update TASK_LOST for task 644b59eb-fb20-43fd-a7c1-b1d9406cbfcb of framework d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-0002 'Slave 10.7.1.13 removed: health check timed out'
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: W0206 15:53:16.928638 2670 master.hpp:2113] Master attempted to send message to disconnected framework d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-0002 (arangodb3) at scheduler-7870582e-becd-4747-aeba-0217e91d537e@10.7.1.13:19866
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: I0206 15:53:16.928747 2670 master.cpp:6759] Notifying framework d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-0003 (arangodb3-standalone) at scheduler-180f6695-f3c9-4da6-80e8-d1dc633ec737@10.7.1.13:3583 of lost agent d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-S0 (10.7.1.13) after recovering
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: W0206 15:53:16.928761 2670 master.hpp:2113] Master attempted to send message to disconnected framework d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-0003 (arangodb3-standalone) at scheduler-180f6695-f3c9-4da6-80e8-d1dc633ec737@10.7.1.13:3583
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: I0206 15:53:16.928894 2670 master.cpp:6759] Notifying framework d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-0002 (arangodb3) at scheduler-7870582e-becd-4747-aeba-0217e91d537e@10.7.1.13:19866 of lost agent d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-S0 (10.7.1.13) after recovering
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: W0206 15:53:16.928905 2670 master.hpp:2113] Master attempted to send message to disconnected framework d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-0002 (arangodb3) at scheduler-7870582e-becd-4747-aeba-0217e91d537e@10.7.1.13:19866
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: I0206 15:53:16.928921 2670 master.cpp:6759] Notifying framework d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-0004 (arangodb3-1) at scheduler-f4f3a3f0-2261-4aaf-9390-81f4b1cc6d20@10.7.1.13:25366 of lost agent d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-S0 (10.7.1.13) after recovering
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: W0206 15:53:16.928928 2670 master.hpp:2113] Master attempted to send message to disconnected framework d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-0004 (arangodb3-1) at scheduler-f4f3a3f0-2261-4aaf-9390-81f4b1cc6d20@10.7.1.13:25366
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: I0206 15:53:16.928941 2670 master.cpp:6759] Notifying framework d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-0001 (metronome) at scheduler-4eb937a4-9a64-4a47-9245-3858defe691a@10.7.1.12:41077 of lost agent d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-S0 (10.7.1.13) after recovering
lut 06 15:53:16 arangodb2.test1.fgtsa.com mesos-master[2661]: I0206 15:53:16.928963 2670 master.cpp:6759] Notifying framework d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-0000 (marathon) at scheduler-02bf4e29-4dd7-4cf8-b14b-4a064b4d082c@10.7.1.12:43643 of lost agent d44b38bf-f35b-4c47-8dfb-d53b543b5e8f-S0 (10.7.1.13) after recovering
rest of the journals (`journalctl ...) are empty.
There is also this error in ZooKeeper logs 
I will be grateful for any suggestions on how to investigate it further.
EDIT:
I managed to run it agent node manually by starting dcos-mesos-slave service (before that I had to start dcos-spartan and dcos-gen-resolvconf services). Any ideas why it didn't start automatically?
