Like the title says, I upgraded my service from 500mb to 1gb(only because it was gonna be cheaper) and prior to doing so Ive had 0 service issues. Since then I have had 4 replaced routers, all connections in the box outside(the one on my house) and most recently(3 days ago) they ran a completely new line from the street to my house. After replacing the my router 4 times within the first week and a half my service worked for all but a couple days a month but now it has been up and down and barely working for the last 3 weeks and I can't get a tech out until the 27th. Basically my service signal fluctuates immensely from 500 mb down to . 00mb/s (no seriously I had a speed test that showed . 00) and it's inconsistent, one minute it will be fine then within 30 seconds it is gone and sometimes I can watch the speed tanking mid speed test. This will usually last for 30 minutes at a time and then goes back to normal without me even doing anything. It's usually in the evenings that this occurs but it happens throughout the day. This most recent time they downgraded me to 500mb again and it was still fluctuating and able to watch it decrease on speed tests so they put it back.

At this point idk what to do, the odd thing is that my upload is always perfectly fine. The only thing that hasn't been done is replacing the cable from the box outside into the modem (because what was provided wasn't long enough and when I asked the 1at tech he said it wouldn't cause an issue?) the issue is that the one provided with the new cable is a netcees rg6 trishield 77% nec 820 catV (Etl)us cable and the old cable is a U-Jin/tfc-t10 catV (Ul) series 6 18 Awg cable.

Would that have any effect? And if not any ideas? I don't think it is from signal not reaching because I had 0 service issues prior to upgrading.