My older MacBook Pro keeps loosing connection to the Wi-Fi server

You are connecting using 802.11ac rules, and have established an 80 MHz wide connection on channel 48 (which includes every channel from 36 through 48).

Your RSSI signal strength at -51 is good, (-40 is about the best, and -65 is marginal).

Noise at -92 suggests there MIGHT be other Routers on your channel.

Transmit speed of 780 is the highest for TWO antennas at MCS Index 9. Doesn't that Router have FOUR antennas?

My 15 in MacBook Pro achieves 1170 with similar RSSI and noise numbers, implying there are THREE antennas. It is possible you have a disconnected antenna.

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Because it is possible you may have another Router on your channel, you should investigate what router is on what channel around you.

usually, we just arm-wave the issue by

setting the Router to "automatic" channel selection. Then when the Router powers up, it listens momentarily to what is already on the air, and adjusts to the least-busy channel.

it is not an accident that every debugging procedure starts with "cycle the power to your Router."

The next level we can use is to use the SCAN tool in Wireless Diagnostics to look around at what is visible over the air around the Mac. This has the advantage of showing what is seen at the Mac, which may be slightly different than what is seen at the Router(s). Click on the channel heading to sort by channel.

this is what it looks like:

(drag and drop on Preview to see larger, or make your own)

There are also low-cost third-party tools available for easier debugging

Parece que o problema é no seu MacBook Pro 2015, que pode não estar funcionando bem com o roteador WiFi 7 novo. O Sierra é uma versão antiga do macOS e pode ter dificuldade com roteadores modernos.

Tenta esquecer a rede no MacBook Pro e conectar de novo pra limpar as configurações. Se der, atualiza o sistema pra versão mais nova que ele suporta.

Testa também usar cabo com adaptador pra ver se o problema some. Veja se o roteador tem atualização de firmware.

Como o MacBook Air não tem problema, o MBP pode estar com algum conflito de hardware ou software.

Faz backup e, se nada melhorar, pensa em levar pra assistência ou usar um adaptador Wi-Fi USB.

auto translate fro Portuguese(Brazil) :

It seems that the problem is with your MacBook Pro 2015, which may not be working well with the new WiFi 7 router. Sierra is an old version of macOS and can have problems with modern routers.

Try forgetting the network on your MacBook Pro and connecting again to clear the settings. If possible, update the system to the latest compatible version. Also try using the cable with adapter to see if the problem goes away.

See if your router has a firmware update. Since MacBook Air has no issues, MBP may have some hardware or software conflict.

Back it up, and if nothing improves, think about taking it for help or using a USB Wi-Fi adapter.

Your posted report says you were connected to an access point named TP-Link_3130 at the time of the report.

Using Wireless Diagnostics is a little complicated.

Hold Option while you click on the Wi-FI Icon on the Menubar. You get a screen like this one:

DO NOT (Continue)

Instead, from the Window menu, choose one of the functions available -- in this case SCAN:

Your Mac scans the entire Wi-Fi spectrum it can access, and shows a display like this one:

if you click on the 'Channel' column, it will sort by channel number.

Please post your screenshot.

Wi-Fi Radio Signals from your Router fall off as the cube of the distance. Provided you are close to your Router and have clear line of sight and no competition from neighbors' Routers or known interference producers like microwave ovens.

All others need to do a more careful analysis to find out what is happening.

Wireless diagnostics:

Hold down the Option key while you click on the Wi-Fi icon on the menubar to open up the tools for investigating and fixing Wi-Fi issues

First is "Open Wireless diagnostics", which opens the wireless diagnostics Assistant, but does not proceed.

There are about eight different things you can do from here, but the top-level is to choose Diagnostics off the Window menu, or simply click continue, to do a quick check for Gross misconfiguration or operating problems. Your Admin password will be required. If any recommendations are shown, you should consider then seriously.

Next is to hold down the Option key and click the Wi-Fi icon as before. The screen that opens shows operating parameters of your Wi-Fi network. Screenshot, transcribe, or photograph the results and post back in a reply on the forums. Looks like this older one.

At 80 MHz channel width, EVERY access point from channel 36 through channel 48 is using the same portion of the spectrum, and yours, previously reported with -51 RSSI is not remarkably stronger than some others. Manto at signal strength -75 definitely will interfere with yours, as will some others.

The usual way we do this with ONE Router and No boosters is to set the Router to "automatic" channel selection. Then when the Router powers up, it listens momentarily to what is already on the air, and adjusts to the least-busy channel.

it is not an accident that every debugging procedure starts with "cycle the power to your Router."

The next level we can use is to use the SCAN tool in Wireless Diagnostics to look around at what is visible over the air around the Mac. This has the advantage of showing what is seen at the Mac, which may be slightly different than what is seen at the Router(s).

Did you check the SCAN to see if other Routers are using channels that overlap yours?

Did you check for a disconnected antenna?

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You have NEVER been able to reliably copy MacOS and have it work correctly. In general, neither the copy nor the copy of the copy will work correctly.

For macOS after from 10.15 Catalina onward, you are precluded from using any but fundamental sources (direct downloads or downloaded Installers from Apple) to create the crypto-locked Virtual System Volume.

Best Practice when you are having trouble is to do a Clean Install with sources from Apple, not copies.

Your Mac has Internet Recovery in its ROM, but if your Wi-FI is shaky, you might want to create a bootable installer in addition:

Create a bootable installer for macOS - Apple Support

Some readers here, including me, swear by this inexpensive Utility named WiFi Explorer, available on the Mac App Store. it claim to fame is that it provides a graphic representation of channel usage in its "spectrum" display. here is an example of a very crowded network where nothing is working correctly:

<< In my network part of the sys pref I do believe I have it set to Automatic.. >.

The Access Point chooses the channel. The Mac is a slave to whatever it receives over-the-air.

The setting I am referring to is Inside your Access Point/Router, it is NOT on your Mac.Tp-Link 3130 manual

I do not agree with rtdro assessment above, and in my opinion, the issues are caused by the very crowded Wi-Fi environment the original author, George Mauro, is facing.