# RC7620 network time incorrect by up to 2 minutes **URL:** \ **Category:** Uncategorized\ **Created:** [September 29, 2025, 2:49pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952 "2025-09-29T14:49:42Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![jack.heaffey](https://avatars.discourse-cdn.com/v4/letter/j/ad7895/32.png) [@jack.heaffey](https://forum.legato.io/u/jack.heaffey)\ **Post date:** [September 29, 2025, 2:49pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/1 "2025-09-29T14:49:42Z")
Hi, I’m using modemmanager to control a Sierra Wireless RC7620 device. The time returned by the mm\_modem\_time\_get\_network\_time() function of the modemmanager API is up to 2 minutes earlier than real time. Sometimes the time is 55 seconds earlier than real-time, sometimes it is 30 seconds earlier than real-time, the time offset to real-time varies. Any thoughts as to why this may be happening? ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [September 29, 2025, 2:56pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/2 "2025-09-29T14:56:57Z")
have you checked AT+CCLK? to see whether the clock of the module is correct? ---
**Author:** ![jack.heaffey](https://avatars.discourse-cdn.com/v4/letter/j/ad7895/32.png) [@jack.heaffey](https://forum.legato.io/u/jack.heaffey)\ **Post date:** [September 30, 2025, 10:33am UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/3 "2025-09-30T10:33:28Z")
Yes, the time is still incorrect (by 21 seconds). I have also updated the modem firmware to be the latest (version 10). I have also updated the MBPL to be the latest. ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [September 30, 2025, 10:36am UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/4 "2025-09-30T10:36:02Z")
Without connecting USB, can you connect the module’s UART to windows to check AT+CCLK? ---
**Author:** ![jack.heaffey](https://avatars.discourse-cdn.com/v4/letter/j/ad7895/32.png) [@jack.heaffey](https://forum.legato.io/u/jack.heaffey)\ **Post date:** [September 30, 2025, 10:42am UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/5 "2025-09-30T10:42:20Z")
Sadly I’m not able to do that. I only have access to the USB interface of the module, on a Linux host, and I am using /dev/ttyUSB2 to send AT commands ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [September 30, 2025, 10:43am UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/6 "2025-09-30T10:43:36Z")
then what is changing the time wrongly? Linux? Network ? ---
**Author:** ![jack.heaffey](https://avatars.discourse-cdn.com/v4/letter/j/ad7895/32.png) [@jack.heaffey](https://forum.legato.io/u/jack.heaffey)\ **Post date:** [September 30, 2025, 10:53am UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/7 "2025-09-30T10:53:06Z")
It seems to me to be an issue with the modem. I would expect running “AT+CCLK?” to return the correct time, at least to be accurate to a few seconds. Is the NITZ time known to be inaccurate up to 2 minutes? ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [September 30, 2025, 11:01am UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/8 "2025-09-30T11:01:28Z")
I don’t see problem with my module: ```auto ``` +CEREG: 1,“2775”,“360A20”,7 at+cgdcont? +CGDCONT: 1,“IP”,“smartone”,“0.0.0.0”,0,0,0,0 +CGDCONT: 2,“IP”,“internet”,“0.0.0.0”,0,0,0,0 +CGDCONT: 3,“IPV4V6”,“sos”,“0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0”,0,0,0,1 OK at+cclk? +cclk: “25/09/30,10:59:56+32” OK ati3 Manufacturer: Sierra Wireless, Incorporated Model: RC7620-1 Revision: SWI9X07H\_00.09.10.00 85890e jenkins 2023/09/25 03:16:56 IMEI: 353635110212345 IMEI SV: 29 FSN: 7T118701512345 +GCAP: +CGSM OK at!impref? !IMPREF: preferred fw version: 00.09.10.00 preferred carrier name: GENERIC preferred config name: GENERIC\_001.164\_000 preferred subpri index: 000 current fw version: 00.09.10.00 current carrier name: GENERIC current config name: GENERIC\_001.164\_000 current subpri index: 000 OK at!gstatus? !GSTATUS: Current Time: 65 Temperature: 32 Modem Mitigate Level: 0 ModemProc Mitigate Level: 0 Reset Counter: 1 Mode: ONLINE System mode: LTE PS state: Attached IMS reg state: UNKNOWN IMS mode: Not Support IMS Srv State: UNKNOWN SMS,UNKNOWN VoIP LTE band: B1 LTE bw: 15 MHz LTE Rx chan: 374 LTE Tx chan: 18374 LTE CA state: INACTIVE EMM state: Registered Normal Service RRC state: RRC Idle PCC RxM RSSI: -56 RSRP (dBm): -93 PCC RxD RSSI: -80 RSRP (dBm): -117 Tx Power: – TAC: 2775 (10101) RSRQ (dB): -18 Cell ID: 00360A20 (3541536) SINR (dB): -2.4 OK ---
**Author:** ![jack.heaffey](https://avatars.discourse-cdn.com/v4/letter/j/ad7895/32.png) [@jack.heaffey](https://forum.legato.io/u/jack.heaffey)\ **Post date:** [September 30, 2025, 1:04pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/9 "2025-09-30T13:04:12Z")
It seems that after turning the modem off and back on again quickly, it keeps the previous time. However if I power the modem off, then wait 30 seconds, then power the modem again, the response from AT+CCLK? is “80/01/06,00:00:00”, then after 20 seconds or so the time becomes correct, which is expected behaviour. Perhaps the modem isnt being shut off correctly. Do you know of a way to reset the time on the modem and trigger it to get the time from NITZ again? ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [September 30, 2025, 2:04pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/10 "2025-09-30T14:04:23Z")
You can use at+cfun=0 to enter flight mode. And then reset the clock to all zero. And then at+cfun=1 to ask for network registeation ---
**Author:** ![jack.heaffey](https://avatars.discourse-cdn.com/v4/letter/j/ad7895/32.png) [@jack.heaffey](https://forum.legato.io/u/jack.heaffey)\ **Post date:** [September 30, 2025, 2:24pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/11 "2025-09-30T14:24:01Z")
Thank you for the help so far. I tried that but it didnt seem to invoke the module to get time from NITZ again. By “reset the clock to all zero”, I ran the following command AT+CCLK=“80/01/06,00:00:00+00” Is this correct? ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [September 30, 2025, 2:47pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/12 "2025-09-30T14:47:53Z")
yes, i think so, you can double check by AT+CCLK? after setting to all zero ---
**Author:** ![jack.heaffey](https://avatars.discourse-cdn.com/v4/letter/j/ad7895/32.png) [@jack.heaffey](https://forum.legato.io/u/jack.heaffey)\ **Post date:** [September 30, 2025, 2:56pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/13 "2025-09-30T14:56:57Z")
Yeah if I run “AT+CCLK?” and the response is indeed: “80/01/06,00:00:00+00” After running “AT+CFUN=1”, the modem never updates its time to real time, it just increments every second since “80/01/06,00:00:00+00” ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [September 30, 2025, 3:02pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/14 "2025-09-30T15:02:01Z")
then how about you reset the module by AT+CFUN=-1,1? Can it update the time? ---
**Author:** ![jack.heaffey](https://avatars.discourse-cdn.com/v4/letter/j/ad7895/32.png) [@jack.heaffey](https://forum.legato.io/u/jack.heaffey)\ **Post date:** [September 30, 2025, 3:36pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/15 "2025-09-30T15:36:38Z")
I presume you mean AT+CFUN=1,1 rather than AT+CFUN=-1,1? I tried AT+CFUN=-1,1 and that returned an error Using AT+CFUN=1,1 rebooted the modem but the time did not update. ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [September 30, 2025, 4:00pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/16 "2025-09-30T16:00:47Z")
you can try UDP communication to NTP server and manually decode the NTP to update your +CCLK manually": > **[How to detect if NTP server cannot be reached](https://forum.sierrawireless.com/t/how-to-detect-if-ntp-server-cannot-be-reached/33879/10)** > > I have just made a test with my HL7802 with GSM network here. I found that the CCLK time is updated after starting some UDP communication: ati3 HL7802.4.6.9.4 OK at+cpin? +CPIN: READY OK at+ksrat? +KSRAT: 0 OK at+ksrat=2 OK at+cfun=1,1 OK ... ---
**Author:** ![jack.heaffey](https://avatars.discourse-cdn.com/v4/letter/j/ad7895/32.png) [@jack.heaffey](https://forum.legato.io/u/jack.heaffey)\ **Post date:** [September 30, 2025, 4:50pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/17 "2025-09-30T16:50:03Z")
My application already uses NTP. However there is a need for some users to get the time via NITZ due as they are using custom APNs with no internet access ---
**Author:** ![jack.heaffey](https://avatars.discourse-cdn.com/v4/letter/j/ad7895/32.png) [@jack.heaffey](https://forum.legato.io/u/jack.heaffey)\ **Post date:** [September 30, 2025, 4:51pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/18 "2025-09-30T16:51:06Z")
As an aside, I tried to downgrade the firmware version on the modem back to version 8, which is what I was using before, and now the modem is stuck in a bootloop. I have just enough time to send AT!BOOTHOLD and I get an OK response, yet it reboots still. Any way to stop a bootloop? ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [September 30, 2025, 5:20pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/19 "2025-09-30T17:20:03Z")
it could be the network problem as you mentioned that it can be updated at the beginning BTW, have you tried other network operator and see if the NITZ time is correctly reported? ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [September 30, 2025, 5:20pm UTC](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952/20 "2025-09-30T17:20:56Z")
here says there is anti-rollback mechanism in R10 to downgrade to previous version : [https://source.sierrawireless.com/resources/airprime/software/rc76xx/rc76xx-firmware-release-10,-d-,0/#sthash.ogfG5ZKu.dpbs](https://source.sierrawireless.com/resources/airprime/software/rc76xx/rc76xx-firmware-release-10,-d-,0/#sthash.ogfG5ZKu.dpbs) [Next page](https://forum.legato.io/t/rc7620-network-time-incorrect-by-up-to-2-minutes/6952.md?page=2)