Hi There. I am Bing and I look forward to helping you with your issue today.
Is this the product you are referring to?
I am thinking what are the steps for you to reconnect the device, not to connect your computer. :)
Did you try using its Auto Connect Button?
Is below your topology to test the extender?
<your computer> 188.8.131.52 <-> 184.108.40.206 <home router facing internet> <-> ?.?.?.? <extender> ) ) ) ) 220.127.116.11 <mobile device>
where <-> means ethernet connection while ))) means wireless
IPs 1.1.1.x are for example, the actual IPs like 192.168.x.x depend on your existing configuration. Please advise if you know.
You do mean your computer and secondary router are now internet accessible. Okay, if so, please advise the IPs of your computer and secondary IP. How is your main router connected?
What's the point for you to use 2nd router here?
Okay, your main router is internet facing over its cable connection. your 2nd router sounds like working as an AP only, not a router if its WAN port is not connected at all. If this is the case, one your Mac, change its IP from DHCP to manual with IP 192.168.2.250.
Once done (changes applied), use your Mac's browser to visit 192.168.2.254, you should be able to see your extender's web console. Then change extender's IP to 192.168.1.5 if allowed.
Once finished, change your Mac's IP back to Auto then you can access all routers and extender (192.168.1.5) at the same time.
I assume all masks are 255.255.255.0. If any device you mentioned is using a different subnet mask, that could be a problem. You must tell me the correct information.
Check the screenshot attached. Change your settings per given example.
Be aware that once change to the given IP, you won't able to access the internet, you can only access the extender.
Change the extender's IP to 192.168.1.5, then change you Mac's IP back to Auto, then you can see all of them.
Any feedback please?