Named issues with T-Mobile 5G for Business

[Philip Prindeville]

> On Jan 6, 2026, at 1:30 PM, Richard Laager via bind-users <bind-users at lists.isc.org> wrote:
> 
> On 2026-01-06 14:23, Philip Prindeville via bind-users wrote:
>> A lot of core routers do random drop on ICMP to avoid denial-of-service attacks since ICMP isn't fastswitched (i.e. it takes the CPU to process the packets instead of ASICs).
>> At least that was the case 20 years ago when I was at Cisco.
> 
> Sure, but isn't your MTR showing packet loss all the way to the final destination?
> 
> You had this:
>> 12. ns-1707.awsdns-21.co.uk          66.1%    56   73.2 207.4  73.2 1275. 339.7



Well yes, yes it did.

I noticed that if I disabled recursion it didn’t make any difference.

Restarting the daemon I see:

Jan  6 15:23:15 OpenWrt2 named[24658]: resolver priming query complete: timed out
Jan  6 15:23:15 OpenWrt2 named[24658]: managed-keys-zone: Unable to fetch DNSKEY set '.': timed out


And if I modify isc-dhcp to hand out 1.1.1.1 and 1.0.0.1 as name servers instead, things don’t work any better, so yeah… looks like a packet loss issue.

Which is weird, because when speediest does manage to run, I sometimes see 630/95mbs … other times… 45/19mbs.