Out of two almost identical Windows PCs in the office, one works fine, but the other one downloads fast only from the sites that are nearby (by nodes). Our internal LAN is of more than adequate speed.
Ping gives the same speed for both. It seems only TCP transfers depends on the number of nodes between.
(it claims it uses TCP) gives fast transfer speed to NY for both PC (we're located in NJ), but to CA it slow for one PC and fast for the other.
LAN is separated from the internet by a firewall (Sonicwall TX170) with NAT
My first question is, - what software should I use for diagnostics, and the second, of course, how can I fix the problem.
My wild guess is that the acknowledge packets generated by the PC with the speed problem are corrupted somehow and then they are lost somewhere on the way back. Does that make sense?