Sorry for the delay in response.
As per syslog message . WAN IP of R201 is renewed every 1 hour interval. In this cases ,you may not get internet for few seconds .
Please ask your ISP to increase DHCP Lease time(24 Hrs Durations) for your R201 device.
Please send the tech support logs of E400 to further investigate this issue and arrange a remote session to analyse this issue.
Syslog Message.
<Mon Jul 10 17:54:20 2017> kernel: Wireless: Rcv DIS-ASSOC From 9c:f4:8e:57:8d:46
<Mon Jul 10 17:56:34 2017> udhcpc[5135]: Sending renew...
<Mon Jul 10 17:56:34 2017> udhcpc[5135]: Lease of 172.17.50.22 obtained, lease time 3600
<Mon Jul 10 17:56:43 2017> udhcpc[5543]: Sending renew...
<Mon Jul 10 17:56:43 2017> udhcpc[5543]: Lease of 172.17.50.43 obtained, lease time 3600
<Mon Jul 10 17:57:08 2017> provision[18366]: start to check config file
<Mon Jul 10 17:57:08 2017> provision[18366]: Update configuration fialed, retry 3600 s later
<Mon Jul 10 17:58:05 2017> DEV_MANAGER[18624]: Not able to find [ device_id ] in keystore
<Mon Jul 10 17:58:09 2017> DEV_MANAGER[18624]: Error response: [{"error":{"level":"error","message":...
<Mon Jul 10 17:58:09 2017> DEV_MANAGER[18624]: Unable to discover cnMaestro URL (re-discover in 327 ...
<Mon Jul 10 17:58:09 2017> DEV_MANAGER[18624]: Attempting (re)connection in 5 minutes
<Mon Jul 10 18:01:47 2017> udhcpd[10928]: Sending OFFER of 192.168.11.121
<Mon Jul 10 18:01:47 2017> udhcpd[10928]: Sending ACK to 192.168.11.121
<Mon Jul 10 18:03:38 2017> DEV_MANAGER[18624]: Not able to find [ device_id ] in keystore
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<Mon Jul 10 18:03:42 2017> DEV_MANAGER[18624]: Error response: [{"error":{"level":"error","message":...
<Mon Jul 10 18:26:28 2017> DEV_MANAGER[18624]: Unable to discover cnMaestro URL (re-discover in 339 ...
<Mon Jul 10 18:26:28 2017> DEV_MANAGER[18624]: Attempting (re)connection in 5 minutes
<Mon Jul 10 18:26:34 2017> udhcpc[5135]: Sending renew...
<Mon Jul 10 18:26:34 2017> udhcpc[5135]: Lease of 172.17.50.22 obtained, lease time 3600
<Mon Jul 10 18:26:44 2017> udhcpc[5543]: Sending renew...
<Mon Jul 10 18:26:44 2017> udhcpc[5543]: Lease of 172.17.50.43 obtained, lease time 3600