XPost: comp.mobile.android, alt.comp.os.windows-10   
   From: patrick@oleary.com   
      
   On Thu, 22 Feb 2024 16:04:56 +0000, Graham J wrote:   
   >> 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.   
      
   C:\Windows\system32> netsh interface ipv4 show config "eth0"   
      
   Configuration for interface "eth0"   
       DHCP enabled:                         No   
       IP Address:                           192.168.1.123   
       Subnet Prefix:                        192.168.1.0/24 (mask 255.255.255.0)   
       Default Gateway:                      192.168.1.1   
       Gateway Metric:                       1   
       InterfaceMetric:                      35   
       Statically Configured DNS Servers:    1.1.1.1   
                                             8.8.8.8   
       Register with which suffix:           Primary only   
       Statically Configured WINS Servers:   None   
      
      
   > You may have a good reason for configuring the desktop PC with a static   
   > IP.  Please tell us why.   
      
   I configured the PC years ago, so I don't remember even how I configured it.   
   It doesn't matter to me what its IP address is as long as it works.   
      
   I had probably configured it following a guide such as this one I found now.   
      
   How To Set Up A Repeater Bridge in DD-WRT   
   https://blog.flashrouters.com/2021/07/19/how-to-set-up-a-repeater-bridge/   
      
   > 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.   
      
   Notice in the above they "Disable DNSMasq" (which I also have disabled).   
   And notice they also "DHCP Server: Disable" (which I have disabled).   
      
   I'm sure I followed a guide on the DD-WRT website which disabled both of them.   
   So you are correct. The Repeater Bridge has both of those things disabled.   
      
   But I think my mistake is I don't need the router set up as a repeater   
   bridge to connect it to the phone hotspot. I just need it as a router.   
      
   And the PC can plug into that router just as if it was any other router.   
      
   I'm slowly coming to the realization that my fault is I was trying to   
   keep the repeater bridge - but I don't need the repeater bridge in the   
   emergency temporary situation of the Internet going out on me.   
   https://wiki.dd-wrt.com/wiki/index.php/Bridging   
      
   > 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 IP address of the DD-WRT device is assigned in the setup.   
   It's static.   
      
   It's how all the setup instructions say to do it.   
   https://blog.flashrouters.com/2021/07/19/how-to-set-up-a-repeater-bridge/   
      
   >   
   >> 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?   
      
   See above netsh interface ipv4 show config "eth0" which shows the main   
   router to be at 192.168.1.1   
      
      
   C:\Windows\system32>tracert 192.168.1.1   
   Tracing route to 192.168.1.1 over a maximum of 30 hops   
     1     1 ms     1 ms     1 ms  192.168.1.1   
   Trace complete.   
      
   Surprisingly, the PC doesn't even see the DD-WRT nor the AP as it only   
   sees the gateway in a single hop (interestingly so).   
      
   >> 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.   
      
   Yup. I'm sure it is. And that's part of the root of the problem I had.   
      
   > 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.   
      
   I slowly came to the realization that I was thinking about it all wrong.   
      
   [continued in next message]   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)