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From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Thu, 24 May 2018 17:04:53 +0200
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Subject: Re: [wireguard-android] 'roaming' from LTE to WiFi with version
 0.0.20180523
To: nnet <nnet@fastmail.fm>
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It would appear that T-Mobile is using 464XLAT and Android runs
https://github.com/toreanderson/clatd

Can you confirm this suspicion by sending the output of `ip addr show`
and `ps|grep clat`?