Sugiro averiguar a Tomada. Se for possível colocar o Modem em outro comodo da casa com outro cabo de rede e fazer os testes, seria bom.
Estes testes já foram feitos no quarto onde esta o computador e na sala, ligados em fases elétricas diferentes, com fontes original e uma outra de mais corrente, com filtro e sem filtro.
Agora que voltei da rua depois de várias horas, onde tinha deixado abaixando um arquivo de vídeo grande com o modem ligado direto, com o fio de rede que veio com ele, estava sem internet. A rede parecia estar bem, mas sem internet. Isso acontece várias vezes ao dia. Acontecia com o Linksys, e agora acontece com o TP-Link.
Por enquanto, as únicas variáveis que me parecem com problema são o cabo de rede que vá para a sala e a Velox, com essas quedas sem motivo e os pings altos. Não vejo como o defeito pode ser no hardware novo ou na fonte, já que testei com duas.
Testes entre PC e roteador, com cabo original:
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.
C:\Users\cem>ping -n 50 192.168.1.1
Pinging 192.168.1.1 with 32 bytes of data:
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Reply from 192.168.1.1: bytes=32 time<1ms TTL=64
Ping statistics for 192.168.1.1:
Packets: Sent = 50, Received = 50, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms
C:\Users\cem>
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.
C:\Users\cem>ping -n 50 uol.com.br
Pinging uol.com.br [200.221.2.45] with 32 bytes of data:
Reply from 200.221.2.45: bytes=32 time=36ms TTL=55
Reply from 200.221.2.45: bytes=32 time=41ms TTL=55
Reply from 200.221.2.45: bytes=32 time=40ms TTL=55
Reply from 200.221.2.45: bytes=32 time=51ms TTL=55
Reply from 200.221.2.45: bytes=32 time=42ms TTL=55
Reply from 200.221.2.45: bytes=32 time=43ms TTL=55
Reply from 200.221.2.45: bytes=32 time=46ms TTL=55
Reply from 200.221.2.45: bytes=32 time=32ms TTL=55
Reply from 200.221.2.45: bytes=32 time=32ms TTL=55
Reply from 200.221.2.45: bytes=32 time=36ms TTL=55
Reply from 200.221.2.45: bytes=32 time=35ms TTL=55
Reply from 200.221.2.45: bytes=32 time=46ms TTL=55
Reply from 200.221.2.45: bytes=32 time=52ms TTL=55
Reply from 200.221.2.45: bytes=32 time=33ms TTL=55
Reply from 200.221.2.45: bytes=32 time=32ms TTL=55
Reply from 200.221.2.45: bytes=32 time=44ms TTL=55
Reply from 200.221.2.45: bytes=32 time=40ms TTL=55
Reply from 200.221.2.45: bytes=32 time=53ms TTL=55
Reply from 200.221.2.45: bytes=32 time=35ms TTL=55
Reply from 200.221.2.45: bytes=32 time=34ms TTL=55
Reply from 200.221.2.45: bytes=32 time=39ms TTL=55
Reply from 200.221.2.45: bytes=32 time=36ms TTL=55
Reply from 200.221.2.45: bytes=32 time=38ms TTL=55
Reply from 200.221.2.45: bytes=32 time=47ms TTL=55
Reply from 200.221.2.45: bytes=32 time=46ms TTL=55
Reply from 200.221.2.45: bytes=32 time=42ms TTL=55
Reply from 200.221.2.45: bytes=32 time=38ms TTL=55
Reply from 200.221.2.45: bytes=32 time=54ms TTL=55
Reply from 200.221.2.45: bytes=32 time=36ms TTL=55
Reply from 200.221.2.45: bytes=32 time=33ms TTL=55
Reply from 200.221.2.45: bytes=32 time=32ms TTL=55
Reply from 200.221.2.45: bytes=32 time=53ms TTL=55
Reply from 200.221.2.45: bytes=32 time=34ms TTL=55
Reply from 200.221.2.45: bytes=32 time=39ms TTL=55
Reply from 200.221.2.45: bytes=32 time=39ms TTL=55
Reply from 200.221.2.45: bytes=32 time=48ms TTL=55
Reply from 200.221.2.45: bytes=32 time=31ms TTL=55
Reply from 200.221.2.45: bytes=32 time=36ms TTL=55
Reply from 200.221.2.45: bytes=32 time=33ms TTL=55
Reply from 200.221.2.45: bytes=32 time=32ms TTL=55
Reply from 200.221.2.45: bytes=32 time=52ms TTL=55
Reply from 200.221.2.45: bytes=32 time=36ms TTL=55
Reply from 200.221.2.45: bytes=32 time=45ms TTL=55
Reply from 200.221.2.45: bytes=32 time=39ms TTL=55
Reply from 200.221.2.45: bytes=32 time=38ms TTL=55
Reply from 200.221.2.45: bytes=32 time=34ms TTL=55
Reply from 200.221.2.45: bytes=32 time=39ms TTL=55
Reply from 200.221.2.45: bytes=32 time=32ms TTL=55
Reply from 200.221.2.45: bytes=32 time=37ms TTL=55
Reply from 200.221.2.45: bytes=32 time=39ms TTL=55
Ping statistics for 200.221.2.45:
Packets: Sent = 50, Received = 50, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 31ms, Maximum = 54ms, Average = 39ms
C:\Users\cem>
Nesse teste o ping ficou bem razoável. Só por curiosidade fiz um tracert para miami.com, e deu os mesmos valores do tracert que botei antes.
Você não me falou se aquele AV que você recomenda é gratuito ou não.