# Cannot find network with some HL7688 modules **URL:** \ **Category:** IoT Modules\ **Created:** [December 19, 2019, 9:23pm UTC](https://forum.sierrawireless.com/t/cannot-find-network-with-some-hl7688-modules/18767 "2019-12-19T21:23:12Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Harishk07](https://avatars.discourse-cdn.com/v4/letter/h/76d3ee/32.png) [@Harishk07](https://forum.sierrawireless.com/u/Harishk07)\ **Post date:** [December 19, 2019, 9:23pm UTC](https://forum.sierrawireless.com/t/cannot-find-network-with-some-hl7688-modules/18767/1 "2019-12-19T21:23:12Z")
Hello, We are using the HL7688 module for our Embedded devices and we are able to successfully make data transfer ore create a PDP session and use it. But it is not the same case for all the purchased HL7688. We have found some of the modules are not able to connect to networks with the same setup when we just replace the HL7688 modules and we get following information from AT commands execution. AT+COPS=? +CME ERROR: not found AT+COPS=0 +CME ERROR: no network service But when we change the module there is no problem. Can any of you help us identify what is th e problem? ---
**Author:** ![jerdung](https://avatars.discourse-cdn.com/v4/letter/j/82dd89/32.png) [@jerdung](https://forum.sierrawireless.com/u/jerdung)\ **Post date:** [December 20, 2019, 3:51am UTC](https://forum.sierrawireless.com/t/cannot-find-network-with-some-hl7688-modules/18767/2 "2019-12-20T03:51:07Z")
Hi, Could you help to check these values: - ATi10 - AT\*PSRDBS? - AT+CMEE? - AT+CGDCONT? I guess that these modules are not set correct band, so they can not detect any network. Please set all bands for these modules ( or set correct network band), ex: AT\*PSRDBS=1,315584 Thanks, ---
**Author:** ![Harishk07](https://avatars.discourse-cdn.com/v4/letter/h/76d3ee/32.png) [@Harishk07](https://forum.sierrawireless.com/u/Harishk07)\ **Post date:** [December 20, 2019, 3:23pm UTC](https://forum.sierrawireless.com/t/cannot-find-network-with-some-hl7688-modules/18767/3 "2019-12-20T15:23:28Z")
Hello Jerdung, Thanks for your quick reply, I appreciate it. Please check the following results for the non-working module. **ATi10** Modem-Firmware: RHL7688.A.2.15.1.0.151600.201809181425.x7160\_1 HL7688 HL7688.A.2.15.1.0 x7160 FUSED 2018-09-18 17:14:50 r12946 Primary-Boot: RHL7688.A.2.15.1.0.0202170420.201809181425.x7160\_1 2018-09-18 14:25:00 r10178 Secondary-Boot: RHL7688.A.2.15.1.0.0202170420.201809181425.x7160\_1 2018-09-18 14:25:00 r10178 Update-Agent: RHL7688.A.2.15.1.0.0201160412.201809181425.x7160\_1 2018-09-18 14:25:00 r12946 4G-Firmware: 7160.S3.561.40.4.805.01.5227.18265 3G-Firmware: 202.999.623.43-54.35 OK **AT\*PSRDBS?** \*_ **PSRDBS: 315584** _ OK **AT+CMEE?** +CMEE: 2 OK **AT+CGDCONT?** +CGDCONT: 1,“IP”,"",“0.0.0.0”,0,0 OK From the above results, it seems like the bands are already set to 315584. Please let me know if there are any other things I could potentially check to figure out what the problem is. I tried more AT commands to debug further and found that on non working modules I get the following. **AT+KBND?** **+KBND: 00000000** OK AT+KBND=? +KBND: (0,20,40,800,2000,4000,10000,20000) OK AT+CGREG? +CGREG: 0,4 OK Thanks ---
**Author:** ![AE5000](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/ae5000/32/4828_2.png) [@AE5000](https://forum.sierrawireless.com/u/AE5000)\ **Post date:** [December 20, 2019, 5:22pm UTC](https://forum.sierrawireless.com/t/cannot-find-network-with-some-hl7688-modules/18767/4 "2019-12-20T17:22:38Z")
Hi @Harishk07, What location/country are you using the module? Also what carrier and APN do you plan to test the module with? For the working module, does it have the same firmware, band setting? Can you send us the output of below commands for the working module: - ATi10 - AT\*PSRDBS? - AT+CMEE? - AT+CGDCONT? - AT+COPS? - AT+KBND? - AT+COPS=? - AT+CREG? - AT+CEREG? ---
**Author:** ![Harishk07](https://avatars.discourse-cdn.com/v4/letter/h/76d3ee/32.png) [@Harishk07](https://forum.sierrawireless.com/u/Harishk07)\ **Post date:** [December 20, 2019, 5:35pm UTC](https://forum.sierrawireless.com/t/cannot-find-network-with-some-hl7688-modules/18767/5 "2019-12-20T17:35:37Z")
Hello, I am using the module in USA (EST) with the AT&T network. The APN for the AT&T network that I use is " broadband". The firmware is same for both the modules. A.2.15.1.XXX. Please check the output of the working module on the same setup. Ati10 Modem-Firmware: RHL7688.A.2.15.1.0.151600.201809181425.x7160\_1 HL7688 HL7688.A.2.15.1.0 x7160 FUSED 2018-09-18 17:14:50 r12946 Primary-Boot: RHL7688.A.2.15.1.0.0202170420.201809181425.x7160\_1 2018-09-18 14:25:00 r10178 Secondary-Boot: RHL7688.A.2.15.1.0.0202170420.201809181425.x7160\_1 2018-09-18 14:25:00 r10178 Update-Agent: RHL7688.A.2.15.1.0.0201160412.201809181425.x7160\_1 2018-09-18 14:25:00 r12946 4G-Firmware: 7160.S3.561.40.4.805.01.5227.18265 3G-Firmware: 202.999.623.43-54.35 OK AT\*PSRDBS? \*PSRDBS: 315584 OK AT+CMEE? +CMEE: 2 OK AT+CGDCONT? +CGDCONT: 1,“IP”,“broadband”,“10.120.89.21”,0,0,0,0,0,0 OK AT+COPS? +COPS: 0,0,“AT&T”,7 OK AT+KBND? +KBND: 00000800 OK AT+COPS=? +COPS: (2,“AT&T”,“AT&T”,“310410”,7),(1,“AT&T”,“AT&T”,“310410”,2),(1,“Verizon”,“Verizon”,“311480”,7),(1,"","",“313100”,7),(1,"","",“310830”,7),(1,“T-Mobile”,“T-Mobile”,“310260”,2),(1,"","",“312530”,7),(1,"","",“311882”,7),(1,“Sprint”,“Sprint”,“310120”,7) OK AT+CREG? +CREG: 2,1,“32C1”,“0B992008”,7 OK AT+CEREG? +CEREG: 0,1 OK Please let me know if I can provide you with more information for debugging this issue. ---
**Author:** ![AE5000](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/ae5000/32/4828_2.png) [@AE5000](https://forum.sierrawireless.com/u/AE5000)\ **Post date:** [December 20, 2019, 5:48pm UTC](https://forum.sierrawireless.com/t/cannot-find-network-with-some-hl7688-modules/18767/6 "2019-12-20T17:48:18Z")
Thank you @Harishk07. For the non-working module, can you try to set the APN and give it a try: AT+CGDCONT=1,“IPv4v6”,“broadband” AT+CFUN=4 AT+CFUN=1 Let me know if this helps. ---
**Author:** ![Harishk07](https://avatars.discourse-cdn.com/v4/letter/h/76d3ee/32.png) [@Harishk07](https://forum.sierrawireless.com/u/Harishk07)\ **Post date:** [December 20, 2019, 6:22pm UTC](https://forum.sierrawireless.com/t/cannot-find-network-with-some-hl7688-modules/18767/7 "2019-12-20T18:22:19Z")
Thank you, It did fix the problem. Can please help me understand how changing the IPv4v6 fixed the problem? ---
**Author:** ![AE5000](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/ae5000/32/4828_2.png) [@AE5000](https://forum.sierrawireless.com/u/AE5000)\ **Post date:** [December 20, 2019, 6:44pm UTC](https://forum.sierrawireless.com/t/cannot-find-network-with-some-hl7688-modules/18767/8 "2019-12-20T18:44:54Z")
Hi @Harishk07, I think the solution was to set the APN. Using “IP” or “IPv4v6” should work. I usually recommend “IPv4v6” because it handles dual IP stack UE capability. -Mihir. ---
**Author:** ![Harishk07](https://avatars.discourse-cdn.com/v4/letter/h/76d3ee/32.png) [@Harishk07](https://forum.sierrawireless.com/u/Harishk07)\ **Post date:** [December 20, 2019, 7:20pm UTC](https://forum.sierrawireless.com/t/cannot-find-network-with-some-hl7688-modules/18767/9 "2019-12-20T19:20:00Z")
Thank you!!! I will change our code to use “IPV4V6” instead of “IP” which is the default.