long standing MacOS DHCP issue (many 10.x versions)

[jdw13]

This issue has persisted over many Macs, different routers, and MacOS going back perhaps as far as Mac OS X Public Beta. Many years ago I started "using DHCP with manual IP address" in my configuration at home in order to enjoy a stable internet connection, both over wired ethernet and WiFi. I have been traveling for the last couple of months and have found that over various WiFi connections that my MacBook Pro running High Sierra will degrade, sometimes with only some destinations unreachable, sometimes loosing the Layer 2 WiFi altogether and unable to reconnect on WiFi. Usually I can recover by power off, and then boot up fresh and then I can obtain WiFi connectivity and previously unreachable destinations are reachable. This has happened several times during my time away.

When I have access to the router, rebooting it seems to provide only temporary relief. Since Android and Kindle WiFi connections were fine, I was suspecting hardware but then recalled that ages ago I switched my home to use manual IP assignments. Just as I discovered years ago in my home network, allowing dynamic IP address assignment can sometimes lead to network issues over time. (It is has been so long I do not recall the exact symptoms other than using static IP assignment for all my MacOS devices resolved the problems.)

I cannot find anything online describing similar issues, but I have observed this over the Macs I've owned over the years, and likely with all OS X versions. (I *may* have begun static IP at home with the public beta.)

Can anyone comment on this? I suspect there may be a long-standing bug in the Mac DHCP, perhaps it may cycle through addresses needlessly or get itself into a state that it cannot obtain one, but that would not seem to explain why Layer 2 WiFi would not come up. Perhaps MacOS DHCP and WiFi implemention have some overly strict interpretations of the standards. Whatever is going on, finding the 'dynamic' DHCP IP address in use when up, or selecting one in the router's range, and then configuring it statically with

1. System Preferences
2. Network
3. Advanced
4. TCP/IP
5. Using DHCP with manual IP address

seems to resolve whatever instability is happening.

This may seem quirky but is not as I have observed whatever is going on over many sets of router/Mac/MacOS configurations.

 

[Babmo]

I have similar issues, my 2017 MBP drops WiFi out of the blue. Annoying as hell. I narrowed it down to the router assigning wrong submask and IP, but when I assign correct (what worked a minute ago) values manually nothing happens.

After reboot it‘s always fine, sometimes it will work as suddenly as it stops, after an hour or so. Apple support wasn‘t helpful at all. My 2010 MBP (both on High Sierra) never had this glitch, nor my other devices. I even tried to unplug all the USB-C ports (because Apple would not test if they block the WiFi signal because of frequency — they sometimes do), nothing helps. Annoying as hell.