CCR1016---HexLite EoIP troubles.

Hello.
We have about 100 eoips via Internet between central CCR-1016 and regional HexLites.
All of them (both CCR and HexLites) use real ip adresses.
Periodically, about 2 times a week EoIP tunnels to two or three HexLite go down although the IP connectivity between HexLite and CCR remains active.
The solution in this case is to change the remote-ip on HexLite to another address and after 3-5 return it back on CCR’s ip address.
Is it CCR or HexLite fault and what is the better way to solve the problem?
CCR

 system resource print          
             uptime: 21w4d3h17m33s
            version: 6.30.1
         build-time: Jul/14/2015 11:22:46
        free-memory: 1514.8MiB
       total-memory: 1939.4MiB
                cpu: tilegx
          cpu-count: 16
      cpu-frequency: 1200MHz
           cpu-load: 0%
     free-hdd-space: 432.7MiB
    total-hdd-space: 512.0MiB
  architecture-name: tile
         board-name: CCR1016-12G
           platform: MikroTik

HEX-Lite

 /system resource print
                   uptime: 2w4d21h18m33s
                  version: 6.28
               build-time: Apr/15/2015 15:18:31
              free-memory: 43.4MiB
             total-memory: 64.0MiB
                      cpu: MIPS 24Kc V7.4
                cpu-count: 1
            cpu-frequency: 850MHz
                 cpu-load: 2%
           free-hdd-space: 5.2MiB
          total-hdd-space: 16.0MiB
  write-sect-since-reboot: 118086
         write-sect-total: 118903
               bad-blocks: 0%
        architecture-name: mipsbe
               board-name: hEX lite
                 platform: MikroTik