You put a lot of info to address.
1. 5ghz is much faster than 2.4ghz but because of how it functions, it doesn't broadcast as far or through as much materials. You see a faster drop off in speeds with distance and obstructions.
2. the Iphone 7 supports a link rate of 866 mbps. this is link rate and not throughput. The (usual, not all) way it works is take the link rate and the max throughput rate is usually 55% of that. So theoretically you can get faster than what you have. But thats under optimal conditions. Meaning close to router, no wifi interference, no other issues (other streaming devices).
3. If you test the C7000 with a hardwired connection, what speeds do you get?
4. How are you speedtesting on the iphone? with the nighthawk app or the speedtest app. both have been found to use bad servers sometimes and report slower speeds.
5. any other devices you can test with?
6. In terms of the ps4, the ps4 has had a couple revisions but it was originally 2.4ghz only (https://www.ign.com/wikis/playstation-4/PlayStation_4_Hardware_Specs). If this is the version you have, 2.4ghz struggles with gaming/streaming in a congested environment due to lower bandwidth, easier interference (less channels), and the fact that it does penetrate better/further so more devices can impact its performance. If that's the case, its best to hardwire in the ps4. Can the C7000 be moved to where the ps4 is or is it required to be where it is?
7. You also put that the ps4 is lagging when you're watching tv. You mean streaming tv? or just watching regular content? What device other than the ps4 is streaming?
Btw, 139mbps is more than adequate for streaming. Netflix only needs 20mbps to stream 4k content. But streaming tends to be a bit more sensitive to interference as well. I've hardwired in all my streaming devices for this reason.
