[tcp] nw_proto_tcp_route_init [C1.1:1] no mtu received

Question

Created Dec ’20

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I have simple iOS App running on an iPad using Network.Framework, NWConnection and NWEndpoint to setup a TCP connection to a Microchip RN-171. It all worked fine until iOS 14 when I started to occasionally get this error:

Code Block [tcp] nw_proto_tcp_route_init [C1.1:1] no mtu received

at which point the connection just locks up with no further data flow in either direction is possible with respect to iOS.

Looking at the RN-171 data sheet I see that the default value for mtu is 1524 so I am assuming that during the negotiation between the RN-171 and iOS this value should be set and some change in iOS 14 means that this value doesn't always get to iOS.

Any ideas what the root cause might be and how to fix it?

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Answer 1

DTS Engineer OP

Apple

Dec ’20

Any ideas what the root cause might be and how to fix it?

I asked the networking team about this and we’re not entirely sure what’s going on here. We’d appreciate you filing a bug report about this, making sure to include a sysdiagnose log taken shortly after reproducing the problem.

Once your done, please post your bug number here.

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@apple.com"

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Answer 2

NIMAXA@synctonic.com OP

Mar ’21

Hi, I am running into the exact same issue. Have you figured out any solution to this issue?

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Answer 3

DTS Engineer OP

Apple

Mar ’21

Have you figured out any solution to this issue?

Not sure whether you’re addressing me or venerley but, speaking from my perspective, I’m not able to offer any insight into this. If venerley had posted their bug number I could look up its state but without that I’m not able to find any info. Indeed, I’m not even sure whether it was investigated at all )-:

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

0