When migrating to a new router I remarked my iPhone (7Plus) had lousy TX performance compared to the other 80211.ac Apple devices connected to the same wireless SSID as revealed in below screenshot:


Since it was a new router, I figured maybe there was some inconsistent configuration going on somewhere. Reviewed everything; all good.

Comparative analysis: what's different about this iPhone than the other devices that are working correctly?!?!?

I remarked my iPhone was right next to the router. So I moved it about 4 feet away (in same room). Still terrible TX performance on just this one device. Other than proximity (which I just checked) which can affect wireless performance, why was this iPhone non-performant?!?!?

  • There is something realy strange: the signal of your iPhone is 2 dB above your MBP and only get 1/20 of the bandwidth. Were the 2 of them aligned with the router (iPhone -- MBP -- router)? – dan Aug 14 '19 at 20:17
  • @dan I have a small home office, with ALL the devices in the same room. My iPad and iPhone are on the desk in-line withe the router (iPad at the opposite end of the desk). And I have a laptop table is connected to the desk (it juts-out) that I actually use my Macbook with. My body is between the router and the macbook. In any event, all the gear is in a tiny space, so other than me, no signal impedance from anything. Also, for the sake of completeness,the router is a MikroTik RB4011 – F1Linux Aug 14 '19 at 20:21
  • When you write "in-line with the router" do you mean you have a straight line constituted of iPhone -- iPad -- router? – dan Aug 14 '19 at 20:27
  • @dan Yes: Router at the far edge of the desk near a doorway, with the iPhone & iPad on the same desk. The iPad is on a stand raised off the desk about 5-6 inches. I usually keep the phone a foot or so from the router, but moved it away for my testing. I read that being too close to the router can also result in a gap in coverage. Hence I move the phone to ensure it caught the signal. At the other end of the office behind the iPad is a wall. – F1Linux Aug 14 '19 at 20:30
  • I see. You should avoid to align 2 Wi-Fi equipments with your router because their direct signal will interfere with each others. You are right you also should to put anything too close to the router since this is usually an area where all lines of connection mix together, thus increasing the level of interferences (noise). – dan Aug 14 '19 at 20:35

Nothing to do with the router in the end. The source of the fault was a Layer 1 issue with the iPhone itself (D'Oh!): the case was absolutely CRUSHING TX performance as the screenshot after case was removed from the iPhone shows:


Performance skyrocketed immediately after removing the phone's case.

I always figured there would some degree of a hit from using a phone case on signal performance, but I was absolutely stunned at actually how much there was.

Anyhoo, hope this helps others improve crap performance due to these snazzy phone cases we all love so much ;-)-

The offending case (wood with some sort of rubberized material lining it) is pictured below at Dan's request:

Phone Case

  • This is interesting and useful. I encourage you to upvote your Answer (you can do that), and (after 24 hrs) to click on the "Answered" green check mark. – DavidSupportsMonica Aug 14 '19 at 19:59
  • Please, add what is your iPhone case made of. Do you have any part made of glass or metal in or by it (a credit card with NFC)? – dan Aug 14 '19 at 20:11
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    I don't know. I upvoted my own Answer here: apple.stackexchange.com/questions/366615/…, and will check it off tonight (after 24 hrs have elapsed since posting). I upvoted your Answer. – DavidSupportsMonica Aug 14 '19 at 20:26
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    Yeah, external factors are often the culprits and often something people would never guess. And sometimes it's something that can be obvious, but discounted because it's never been an issue before. For example, I recently troubleshooted someone's network where every now and then some (but not all) of their Apple devices (iPhones/iPads/MacBooks) would suddenly drop their Wi-Fi speeds down to almost nothing - often for only a couple of minutes at a time. – Monomeeth Aug 14 '19 at 22:24
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    I kept asking has anything changed in your environment, kept getting a 'no' answer. Wasn't until I was offered a snack and the iPad I was holding suddenly lost speed that the penny dropped! As soon as they were using the microwave any device connected to the 2.4GHz range dropped out, while those connected to the 5GHz were fine. Apparently they had replaced the microwave 2 weeks earlier and didn't mention it because they'd never had problems with the old microwave and the new one was in exactly the same spot. – Monomeeth Aug 14 '19 at 22:24

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