Same thing happened to me, after the upgrade, no Signal Strength and of course no Internet. 2 2018-10-01 00:02:52 4G Information USER: Registration denied by the visible network! 3 2018-10-01 00:02:05 4G Information WARN: Get SCA fails. CMS ERROR, errno is 500 4 2018-10-01 00:02:05 4G Information ERROR: Set CPMS fails. CMS ERROR, errno is 314 5 2018-10-01 00:01:57 4G Information WARN: Get SCA fails. CMS ERROR, errno is 500 6 2018-10-01 00:01:57 4G Information ERROR: Sim IMSI Response Error! I'll try a firmware downgrade...

Downgrade failed, Error code: 71211.

 

UEG wrote

This is my first contribution to this forum. 
I've recently purchased a 4G wifi router, model MR100, perfectly fitting to my needs. I unboxed it, inserted the sim card, powered up and wow, everything worked fine. Then I had the insane idea of performing a firmware upgrade to 1.3.0 0.9.1 v0001.0 Build 210119 Rel.31129n, and there the troubles started. After rebooting, the router won't connect to internet anymore. The 4G carrier was up and running, but no connection to internet. I checked the APN, performed a factory reset, tried to downgrade the firmware (which was not possible), and in the end contacted Amazon that sent me a new device in exchange for the one that was not working anymore.

I thought that was the end of my problems. Well, I got the new product, unboxed, got it to run, and then decided once again to upgrade the firmware. BAD IDEA. The same issue as with the first device started, and I could not get the router to connect  to internet anymore. I tried to contact TP Link local customer care via telephone and via email, no answer on the phone and my email sent 4 days ago still hasn't  been answered or acknowledged. This is really a shame for TP Link.

I am attaching the logfile, can anyone suggest me anything I can do to resume the internet connection? As you see, LTE/4G connection is fine, it is the internet layer that doesn't work. Thanks!

 

UEG wrote

This is my first contribution to this forum. 
I've recently purchased a 4G wifi router, model MR100, perfectly fitting to my needs. I unboxed it, inserted the sim card, powered up and wow, everything worked fine. Then I had the insane idea of performing a firmware upgrade to 1.3.0 0.9.1 v0001.0 Build 210119 Rel.31129n, and there the troubles started. After rebooting, the router won't connect to internet anymore. The 4G carrier was up and running, but no connection to internet. I checked the APN, performed a factory reset, tried to downgrade the firmware (which was not possible), and in the end contacted Amazon that sent me a new device in exchange for the one that was not working anymore.

I thought that was the end of my problems. Well, I got the new product, unboxed, got it to run, and then decided once again to upgrade the firmware. BAD IDEA. The same issue as with the first device started, and I could not get the router to connect  to internet anymore. I tried to contact TP Link local customer care via telephone and via email, no answer on the phone and my email sent 4 days ago still hasn't  been answered or acknowledged. This is really a shame for TP Link.

I am attaching the logfile, can anyone suggest me anything I can do to resume the internet connection? As you see, LTE/4G connection is fine, it is the internet layer that doesn't work. Thanks!

@UEG