Laying LAN in a purchased prefabricated house - timber frame construction

Here you have to make sure that the router and access point have different IP addresses.

It's like in Highlander, there can only be one. Every device needs its own IP address, otherwise chaos is inevitable. But it is important that the IP range (usually the first 3 numbers in the IPv4 address) is the same. Otherwise, devices cannot find each other.

Electricians can lay cables and usually terminate them on the patch panel or network socket, but for most of them, the networking world ends there. For networks, that's just where it begins.

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Electricians can lay cables and (usually) also terminate them on the patch panel or network socket, but for most of them, the network world ends there. That’s just where networking really begins.

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That is a completely different discipline. Electricians deal with electrical engineering, networks, aside from their electrical basics, are mainly about communication and information technology. Even most master electricians have never heard anything about it.
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Well, don’t be so hard on electricians. I am fully aware of the professional field of a traditional electrician. But even here there are plenty of specialization and training opportunities that go far beyond the classic job profile. I know both personally very well as well as their professional environment. Neither of them works anymore as classic (trained) electricians. Their (network) technical affinity goes far beyond just using a cellphone or similar.

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that not everything works for laypersons without knowledge.
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I fully understand that as well. But as a layperson, you first have to know what knowledge you need for the technology - or whatever it is - to work. Where exactly should the basic knowledge end then?

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that’s why it’s not the evil technology’s fault because it doesn’t work by itself.
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But I do not blame the technology ...

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That can very quickly lead to completely wrong conclusions in this context.
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It can ... but it doesn’t have to :) A carpenter has already helped me with a guess in a totally different field. If I soon find out that – whoever – has problems with an access point and LAN comparable to mine and I can help that person through my hint, the person will surely be grateful. I don’t have to add that otherwise I have no idea.

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Brainstorming is something completely different though. ;)

Yes, brainstorming usually refers to a group. Ideally and depending on the problem, consisting of laypersons (!) as well as experts – also from other specialist groups – and it is much more complex than just making a suggestion. One of the core ideas is to allow no (!) criticism or evaluation of the statements. Because: creative approaches can also develop from initially completely nonsensical proposals.

Do you not have a DHCP that assigns your access point an IP, or was it a used device where the IP was fixed?

Their (network) technical affinity goes well beyond merely operating a phone or something similar.

Sorry, but if that were the case, they would have known about IP addresses. That was already familiar to me as a student, but then we are back to the question of what technical affinity actually means. ;)

Brainstorming

No brainstorming or creativity is needed here, just simple expertise, because the "problem" and its solutions are well known. But if you want your effort for the matter to be recognized, that’s fine with me too. It simply only has to do with network basics, nothing else.

Sorry, ...

It doesn't have to be that way :)

... No brainstorming or creativity is needed here, just simple expertise, ...

I never claimed brainstorming was necessary. Nevertheless, a hint or a guess can also lead to success without immediate expertise ...

Imagine if everyone had the (basic) knowledge to design floor plans. Then we would certainly have significantly fewer posts here.

I rather think then people would be playing "Autoquartett" with floor plans here ;-)