How to keep it steady

[Slender]

I solved my problem. I had the neutral reversed in the PC power outlet. Get a multimeter and make sure the neutral is on the left side of the PC and monitor power cable and not the right side.

Dude. It shouldn't have any effect at all. If you have a normal place, your home.
If it makes you feel better - I've heard of that, a temporary effect

That also solved my problem. It's no coincidence that there's a set order. Hot pin must go to hot pin, otherwise, there'll be a leak.
I had a leak in another breaker/circuit that infected the ground connection on my PC's circuit/breaker. Once I fixed that, the slow mouse stopped. Also, try connecting your PC and router to the same breaker. Don't connect your router to other devices outside the same breaker via Ethernet, and ground the Ethernet cable to a UPS before connecting your PC.

can u explain what u fix?
and what do you mean ground cable? connect ground cable rj45 to ups, and from ups to rounter ungrounded?

[ProGrueso]

I solved my problem. I had the neutral reversed in the PC power outlet. Get a multimeter and make sure the neutral is on the left side of the PC and monitor power cable and not the right side.

Dude. It shouldn't have any effect at all. If you have a normal place, your home.
If it makes you feel better - I've heard of that, a temporary effect

That also solved my problem. It's no coincidence that there's a set order. Hot pin must go to hot pin, otherwise, there'll be a leak.
I had a leak in another breaker/circuit that infected the ground connection on my PC's circuit/breaker. Once I fixed that, the slow mouse stopped. Also, try connecting your PC and router to the same breaker. Don't connect your router to other devices outside the same breaker via Ethernet, and ground the Ethernet cable to a UPS before connecting your PC.

can u explain what u fix?
and what do you mean ground cable? connect ground cable rj45 to ups, and from ups to rounter ungrounded?

Router-rj45-ups-rj45-PC.
I live in a house that was built around the late 1980s, and the wiring was done around that time. Repairing the wiring is going to cost me a lot, so I fixed everything I could in my installation. Curiously, I connected an RJ-45 cable from the router to my UPS and another RJ-45 cable from the UPS to my PC (thinking, "Maybe there's some leak I missed and it's getting into the router (since the router doesn't have a ground connector.")) and you can feel the difference in the hit-reg.
You can Google "My PC got struck by lightning through Ethernet cable" Reddit. There are even videos from Russians showing how lightning blew up their PCs when they were kids. So, ground your RJ-45s.
Also, if, like me, you have an electrical installation from old times... it could be that several of your circuits are not isolated from each other (breakers) and some electrician who has come to work for you to finish the job quickly will take the neutral or ground of a circuit and join it with the phase of another circuit and the energy trying to return to its source causes all kinds of electrical errors that are then transferred to the computer. Think of electricity as the lifeblood of PCs.

[Slender]

Dude. It shouldn't have any effect at all. If you have a normal place, your home.
If it makes you feel better - I've heard of that, a temporary effect

That also solved my problem. It's no coincidence that there's a set order. Hot pin must go to hot pin, otherwise, there'll be a leak.
I had a leak in another breaker/circuit that infected the ground connection on my PC's circuit/breaker. Once I fixed that, the slow mouse stopped. Also, try connecting your PC and router to the same breaker. Don't connect your router to other devices outside the same breaker via Ethernet, and ground the Ethernet cable to a UPS before connecting your PC.

can u explain what u fix?
and what do you mean ground cable? connect ground cable rj45 to ups, and from ups to rounter ungrounded?

Router-rj45-ups-rj45-PC.
I live in a house that was built around the late 1980s, and the wiring was done around that time. Repairing the wiring is going to cost me a lot, so I fixed everything I could in my installation. Curiously, I connected an RJ-45 cable from the router to my UPS and another RJ-45 cable from the UPS to my PC (thinking, "Maybe there's some leak I missed and it's getting into the router (since the router doesn't have a ground connector.")) and you can feel the difference in the hit-reg.
You can Google "My PC got struck by lightning through Ethernet cable" Reddit. There are even videos from Russians showing how lightning blew up their PCs when they were kids. So, ground your RJ-45s.
Also, if, like me, you have an electrical installation from old times... it could be that several of your circuits are not isolated from each other (breakers) and some electrician who has come to work for you to finish the job quickly will take the neutral or ground of a circuit and join it with the phase of another circuit and the energy trying to return to its source causes all kinds of electrical errors that are then transferred to the computer. Think of electricity as the lifeblood of PCs.

hmm, Very interesting. Just a couple of days ago, I was wondering about RJ45 grounding. I thought the current was coming from the ISP's WAN cable to the router. So, I connected the WAN to a UPS, and from the UPS, the LAN to the router. Unfortunately, it didn't work. I'll try doing it as you described.

[ProGrueso]

That also solved my problem. It's no coincidence that there's a set order. Hot pin must go to hot pin, otherwise, there'll be a leak.
I had a leak in another breaker/circuit that infected the ground connection on my PC's circuit/breaker. Once I fixed that, the slow mouse stopped. Also, try connecting your PC and router to the same breaker. Don't connect your router to other devices outside the same breaker via Ethernet, and ground the Ethernet cable to a UPS before connecting your PC.

can u explain what u fix?
and what do you mean ground cable? connect ground cable rj45 to ups, and from ups to rounter ungrounded?

Router-rj45-ups-rj45-PC.
I live in a house that was built around the late 1980s, and the wiring was done around that time. Repairing the wiring is going to cost me a lot, so I fixed everything I could in my installation. Curiously, I connected an RJ-45 cable from the router to my UPS and another RJ-45 cable from the UPS to my PC (thinking, "Maybe there's some leak I missed and it's getting into the router (since the router doesn't have a ground connector.")) and you can feel the difference in the hit-reg.
You can Google "My PC got struck by lightning through Ethernet cable" Reddit. There are even videos from Russians showing how lightning blew up their PCs when they were kids. So, ground your RJ-45s.
Also, if, like me, you have an electrical installation from old times... it could be that several of your circuits are not isolated from each other (breakers) and some electrician who has come to work for you to finish the job quickly will take the neutral or ground of a circuit and join it with the phase of another circuit and the energy trying to return to its source causes all kinds of electrical errors that are then transferred to the computer. Think of electricity as the lifeblood of PCs.

hmm, Very interesting. Just a couple of days ago, I was wondering about RJ45 grounding. I thought the current was coming from the ISP's WAN cable to the router. So, I connected the WAN to a UPS, and from the UPS, the LAN to the router. Unfortunately, it didn't work. I'll try doing it as you described.

Also, think of Ethernet cables as a spider web and the router as the point where they emerge. If you connect everything in your house through Ethernet, you're breaking the insulation of all the breakers and merging them together at the router. So, through Ethernet, you can electrocute all your devices that are working with different power sources from different breakers.
If you can, put your router and your PC on the same breaker, and connect everything else (TVs, consoles, and anything else you connect with Ethernet) to Wi-Fi so that the power from the entire house doesn't merge and go to your PC.
Your UPS will probably slow your internet connection from 1GB to 100MB, so don't panic; try it, and if it works for you, find an Ethernet-Ground adapter that supports your full bandwidth.

[Slender]

can u explain what u fix?
and what do you mean ground cable? connect ground cable rj45 to ups, and from ups to rounter ungrounded?

Router-rj45-ups-rj45-PC.
I live in a house that was built around the late 1980s, and the wiring was done around that time. Repairing the wiring is going to cost me a lot, so I fixed everything I could in my installation. Curiously, I connected an RJ-45 cable from the router to my UPS and another RJ-45 cable from the UPS to my PC (thinking, "Maybe there's some leak I missed and it's getting into the router (since the router doesn't have a ground connector.")) and you can feel the difference in the hit-reg.
You can Google "My PC got struck by lightning through Ethernet cable" Reddit. There are even videos from Russians showing how lightning blew up their PCs when they were kids. So, ground your RJ-45s.
Also, if, like me, you have an electrical installation from old times... it could be that several of your circuits are not isolated from each other (breakers) and some electrician who has come to work for you to finish the job quickly will take the neutral or ground of a circuit and join it with the phase of another circuit and the energy trying to return to its source causes all kinds of electrical errors that are then transferred to the computer. Think of electricity as the lifeblood of PCs.

hmm, Very interesting. Just a couple of days ago, I was wondering about RJ45 grounding. I thought the current was coming from the ISP's WAN cable to the router. So, I connected the WAN to a UPS, and from the UPS, the LAN to the router. Unfortunately, it didn't work. I'll try doing it as you described.

Also, think of Ethernet cables as a spider web and the router as the point where they emerge. If you connect everything in your house through Ethernet, you're breaking the insulation of all the breakers and merging them together at the router. So, through Ethernet, you can electrocute all your devices that are working with different power sources from different breakers.
If you can, put your router and your PC on the same breaker, and connect everything else (TVs, consoles, and anything else you connect with Ethernet) to Wi-Fi so that the power from the entire house doesn't merge and go to your PC.
Your UPS will probably slow your internet connection from 1GB to 100MB, so don't panic; try it, and if it works for you, find an Ethernet-Ground adapter that supports your full bandwidth.

already take apc protectnet but it didnt help.
maybe cuz my tn-c neutral is bad.
anyway, im connect router through ups.
nothing connect to lan only router and 2 pc.
edit: can u photo your rj45 port on ups?