@xc - I am sorry we didn't get it going first time as expected. I hadn't successfully done a network configuration that involved changing the IP address of the second modem to create a single network before - mine have been two separate networks; I have learned some good information regarding the networking peculiarities of this modem and home networks in general - certainly won't forget the WAN MAC! and using a Wi-Fi enabled device in previous network mode may also help. So thankful for @YetAnotherAcc 's guidance and assistance.
YetAnotherAcc - maybe your success in reprogramming the modem's IP address was due to originally using the wireless device which would have been connected in the 192.168.50.x range, meaning no conflict during alterations conducted on the modem's IP address and range, even though it had to be Applied twice. That may explain why you would have had to manually release the Wi-Fi Network SSID and reconnect back in using a new 192.168.0.x IP address. I am retired, so when time permits, I will have another go using your method.
A lot of networking remains a mystery to me. You get to a creating a stage of comfort and generally stay at that level as it meets your needs. Your posts extend my knowledge, so thanks for continually sharing yours with the forum.
YetAnotherAcc - maybe your success in reprogramming the modem's IP address was due to originally using the wireless device which would have been connected in the 192.168.50.x range, meaning no conflict during alterations conducted on the modem's IP address and range, even though it had to be Applied twice. That may explain why you would have had to manually release the Wi-Fi Network SSID and reconnect back in using a new 192.168.0.x IP address.
Nope. I specifically wanted to avoid that possibility which is why I stated "I first changed it to 192.168.0.1 (...) to get it to a standard state. " because I didn't want a subnet change to muddy the test. When I was as 192.168.0.1 my phone received 192.168.0.2 so that was normal.
Your posts extend my knowledge
I try to give reasoning for my thoughts/suggestions whenever possible/practical (my background is testing and writing training software, so its habit) so at least that way people have a chance to learn why things are done and have a better chance of understanding where/why something goes wrong, or a step is missing.
so thanks for continually sharing yours with the forum.
Breaking news update. I still have my [L] plates on, but somehow I have managed to get the two modems to communicate in the suggested single network configuration allowing devices on Modem 2 to access the Internet BUT, after many failed attempts, I had to eventually connect them by a Modem #1 LAN- Modem #2 LAN link, rather than a Modem #1 LAN- Modem #2WAN link, which failed to connect to the Internet for me. This effectively made Modem #2 an Access Point extension of Modem #1.
@xc I can't test the VoIP phone function as my primary modem is with another RSP, so maybe not a full solution for your needs if VoIP requires a WAN link in Modem #2 - the only way I know that a LAN-WAN link between modems can be achieved is with two separate IP address ranges that do not conflict. I am by no means highly experienced in this area and happy to learn.
As a possible alternative for consideration, it is possible to connect a Cordless Phone System, with a long telephone cable subject to area coverage requirements , to the Modem#1 Phone Port to allow your telephone calls to be answered anywhere within your home premises. Some Cordless Phone Systems also come with Repeaters if distance is an issue.
In case of interest, this is what I did. @YetAnotherAcc - try as I could, I couldn't get a LAN-WAN link to work using the same IP Range? I wish Optus hadn't removed the PM feature from the forum.
1. Used iPad to connect to Modem #2 which had previous 192.168.50.1 IP Address.
2. Changed IP address to 192.168.0.2 and range to 192.168.0.3 to 192.168.0.254
3. Disabled DHCP and APPLY.
4. First challenge - "Are you sure? - YES
5. Second Window - "Changes Applied" - long wait with "OPTUS Please Wait" flashing on screen.
6. Wait till it kicks you out of the Browser. Modem #1 Start range edited to 192.168.0.3 with end range left at 192.168.0.254.
7. Linked Modem #1 LAN to Modem #2 WAN. Modem #2 Display shows Internet and WAN LEDs ON.
8. Restarted Modem #2.
9. Restarted iPad and attempted to link it to Optus SSID - "No Internet Error".
Did steps 8 & 9 twice, still "No Internet Error".
10. Changed cable connection to LAN - LAN between modems. Restarted Modem #2 and iPad.
11. iPad assigned 192.168.0.237 after connection to Modem #2 Optus SSID, can log into admin screen on 192.168.0.2, can access Internet, LAN connected PC linked to Modem #2 for Internet on 192.168.0.249. In the Modem #2 list view of devices connected to the single Home Network, I can see another PC LAN connected on Modem #1 with 192.168.0.215 and also Modem#1 IP address 192.168.0.1. Each modem has Wi-Fi connectivity in operation. All DHCP control under Modem#1.
12. I didn't set a Reserved IP Address in Modem #1 for the LAN link to Modem#2 at this stage - just wanted to get Internet access working for test
I suspect why your Modem #2 may have lost its connection is that its IP lease could have expired. In a LAN-LAN network configuration, if you use Modem #2 MAC address on Print Label, its MAC LAN address, for insertion into the Reserved Address section of Modem #1 LAN Settings and SAVE, it should hold up.