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Cablenut9
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Can't get DHCP on non-Mikrotik networks

Thu Jan 14, 2021 4:45 am

I've been having this oddball problem with my mANTbox 19s and Metal 52ac where when in station mode, they can't get DHCP on a network when the access point is not from Mikrotik. I tried everything including factory resets and updating to 6.48. Weirdly, they get DHCP when in station-pseudobridge mode, and I can configure the gateway and IP manually and get network access in station mode. Additionally, when connecting the two devices to each other, DHCP works just fine. Could this be some weird 802.11 incompatibility problem? The security profiles aren't the problem because the same happens when using the default (open) profile on an open network. QuickSet also doesn't help.

One more thing: When I have a Mik device as an AP, the DHCP client gets an address right away so the problem is purely in wireless.
 
mkx
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Re: Can't get DHCP on non-Mikrotik networks

Thu Jan 14, 2021 10:02 am

I've been having this oddball problem with my mANTbox 19s and Metal 52ac where when in station mode, they can't get DHCP on a network when the access point is not from Mikrotik.
Just to verify: if you point a ROS wireless device to third-party AP as client, the ROS device itself can't get DHCP lease ... even if no other device is connected to ROS device? Or is it wired device connected to wireless client providing it LAN connectivity?

As you hinted at the end of your post: 802.11 standard does not allow to build wireless bridges between wired islands ... because client device can not specify MAC address of the original frame source, it can only specify own MAC address (as wireless client identity). Most wifi-gear vendors came up with work-arounds, but they are mostly not compatible. One such work-around is Mikrotik's client-bridge mode, which only works if AP is Mikrotik as well. There are other work-arounds available, you should read the article about wireless client modes to get better picture.
BR,
Metod
 
Cablenut9
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Re: Can't get DHCP on non-Mikrotik networks

Thu Jan 14, 2021 5:23 pm

I have the client ROS device set up as a NAT (in station mode) with its own DHCP server behind that "walled garden" and that part works just fine, so to the non-Mikrotik access point the client device just looks like one thing with one DHCP client. It can ping other devices on the local network, but doesn't know where to route outbound packets because the DHCP client can't get ahold of any info.
 
mkx
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Re: Can't get DHCP on non-Mikrotik networks

Sat Jan 16, 2021 4:16 pm

DHCP client gets all the information from DHCP server. So if clients of your MT DHCP server don't get default route, you should configure DHCP server appropriately.
BR,
Metod
 
Cablenut9
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Re: Can't get DHCP on non-Mikrotik networks

Sat Jan 16, 2021 4:42 pm

DHCP client gets all the information from DHCP server. So if clients of your MT DHCP server don't get default route, you should configure DHCP server appropriately.
That's not the problem, the problem is the DHCP client on the Mikrotik device (NOT the devices behind its NAT) itself can't get DHCP when connecting to a WLAN network.

I actually messed around some more and it seems like a cross-vendor incompatibility problem. The fix is to keep switching the Mik from a/n/ac to n/ac or b/g/n to g/n and eventually it'll connect.

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