XPost: comp.mobile.android, alt.comp.os.windows-10   
   From: nobody@nowhere.co.uk   
      
   Patrick wrote:   
   > On Wed, 21 Feb 2024 21:37:44 +0000, Andy Burns wrote:   
   >> Andy Burns wrote:   
   >>   
   >>> Patrick wrote:   
   >>>   
   >>>> Desktop PC to Android Mobile Hotspot - What do you use for the Gateway?   
   >>>   
   >>> Short answer: leave the desktop using DHCP and it'll Just Work   
   >>   
   >> Maybe your intervening router needs a DHCP helper?   
   >   
   > I do not understand your suggestion.   
   > The desktop has a static IP address (but it could have been assigned by the   
   > gateway for all that it matters). Coming out of the desktop is Ethernet.   
      
   Understood.  It should also therefore have a compatible subnet mask, and   
   a default gateway.  These will enable it to communicate with the   
   internet router.  Conventionally it will have its DNS pointing at the   
   internet router which will forward requests to the ISP's DNS server.   
   Aternatively it may explicitly use an independent DNS server such as   
   8.8.8.8 from Google.   
      
   Please tell us these parameters.   
      
   You may have a good reason for configuring the desktop PC with a static   
   IP.  Please tell us why.   
      
   > The Ethernet goes into the DD-WRT wireless client bridge which DD-WRT calls   
   > a "Repeater Bridge", the other of the 6 choices being "AP", "Station",   
   > "Station Bridge", "Repeater" & "Ad Hoc" for the "Radio Mode".   
   >   
   > There is no obvious setting in the DD-WRT "Repeater Bridge" setup that has   
   > anything to do with DHCP, perhaps because bridges operate at the level of   
   > the MAC address, and as such, are simply pass-through for IP addresses.   
      
   I know nothing of DD-WRT but in the context of its "Repeater Bridge"   
   mode it should not have a DHCP server.  Neither should it have a DNS   
   server.  As you say it passes all such traffic through as if it were a   
   piece of wire.   
      
   But in order for you to communicate with the DD-WRT it needs an IP   
   address/mask.  This must be consistent with the IP address of the   
   desktop PC, and it must not be the same as the IP address of anything   
   else in your system.  It does not need anything for DNS or default   
   gateway unless it needs to get information from the internet.   
      
   We need to understand how the DD-WRT gets its IP address.  Did you put   
   it there?  Is it automatically established by the "Repeater Bridge"   
   mode?  Does it get it by DHCP from the router on the other end of the   
   wireless link?   
      
   > The router is bridged wirelessly to an access point which itself is wired   
   > via a switch into the main router which itself connects to the modem.   
   >   
   > The strange thing is this has been working for years, so I don't think   
   > there is anything wrong with the DD-WRT setup.   
      
   OK so far.  What is the IP address of the main router?   
      
   > But I do wonder what   
   > "gateway" the phone uses since the gateway of 192.168.1.1 wouldn't exist on   
   > the phone's network when used as an access point mobile hotspot.   
      
   You can find this out.   
      
   Connect a laptop to the phone hotspot via WiFi. To avoid confusion first   
   power off everything except the laptop and phone.  Use the command line   
   IPCONFIG /ALL to discover the network address, and specifically the   
   default gateway address allocated to the laptop.  The laptop should be   
   configured to "Obtain an IP address automatically" and "Obtain DNS   
   server address automatically".  These parameters are generated by the   
   hotspot in the phone.   
      
   I expect you to discover that the network address is different from the   
   one established by the internet router.   
      
   [Snip irrelevant part about "DHCP Helper"]   
      
   Now disconnect the laptop from the phone, by disabling its wireless   
   facility.   
      
   Power up the desktop PC and the DD-WRT only.  Establish whether you can   
   still communicate with the DD-WRT.  If it expects to get its IP address   
   from the internet router then this will fail, and you won't be able to   
   communicate with it.  If its IP address is static (regardless of how   
   this was achieved) then communication should be possible.   
      
   At this stage you should be able to change the wireless parameters to   
   suit those required by the phone.  The DD-WRT should then show it is   
   connected to the phone, possibly via a status page of some sort.   
      
   Now connect the laptop BY WIRE to the DD-WRT.  What should happen is   
   that the laptop sends its DHCP request and receives replies from the   
   phone hotspot.  The network parameters should look much the same as when   
   the laptop was connected directly to the phone hotspot earlier in this test.   
      
   You should then be able to browse the internet.   
      
   Now for the desktop PC.  Connect this by wire to the DD-WRT.  The PC is   
   statically configured to communicate with the DD-WRT, but the I expect   
   network address generated by the phone hotspot to be different.  So   
   change the desktop PC to "Obtain an IP address automatically" and   
   "Obtain DNS server address automatically".  It will now no longer   
   communicate with the management page in the DD-WRT but it should   
   communicate THROUGH the DD-WRT to the phone hotspot, and should be able   
   to browse the internet.   
      
      
      
   --   
   Graham J   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)