Thanks David.  You obviously have a lot of experience.  I started with Windows 3.1 myself.   No, the 'Agents' are all connected via ethernet.  I use a star topology to one switch, with distribution from there to one other switch, for each set of 'Agents'.   Thanks for the suggestion re: logging.  I'll look into the VX220-G2v to see what options I have. In terms of evidence so far, I have output from the academic software and at the time it failed, it lost connection to one 'Agent' and then attempted to reassign that calculation to another 'Agent', and then another, and then another. That attempt at reassignment all took place between 03:29:56.85 and 03:29:56.93.  The sofware then reports a communcations failure and stops working.   Ideally, if I can get the main author to make an attempt, I just need to slow down the rate of checking of connection to these 'Agent' PCs.  If it was a mere 1 second, I think that would be enough. Anyhow, as per the OP, I am trying to eliminate whatever 'hiccup' initiated that first problem, and have had some success with DHCP Address Reservation and Static IPs, but it could be coincidental.   Secondly, as you've alluded to, it might be that it is 'all too much' for either the TP-Link ArcherVR1600 or this replacement TP-Link VX220-G2V.   regards Justin ... View more

Thanks David.   Yes, it was written a while ago, probably 15 years past, and it's not in the language that the main author is familiar with.  I expect it was written in C/C++.  The software I use is scientific number crunching so is all DOS. Basically, I want to eliminate DHCP on all of the 'Agent' PCs that talk to the 'Manager' PC, hoping this will help resolve a communications failure that seems to trigger randomly with that software.  I suspect it is caused by 'IP Lease Renewal' on the network, but I'm not sure.  It's a process of elimination.   Having a Static IP (on the network adaptor side) and a DHCP Address Reservation for the 'Manager' PC helped reduce the frequency of the software reporting a communications failure.  At that stage, I just had DHCP Address Reservation only and not Static IP.  Once I added both, it reduced the frequency of problems. I have added other 'Agent' PC, setting Static IPs on each of them, but then ran out of DHCP Address Reservations, hence my request.  I note that I also adjusted the IP Address Pool range, to make sure it is clear of the DHCP Address Reservation. In terms of traffic, there is not much information sent between the 'Agent' PCs and the 'Manager' PC, it's just some numbers.  There are a lot of devices in the house generally, with children with multiple 'things'.  The last crash of the software though was at 3.29am in the morning, so it was not 'prime time'.   Anyhow, as I understand it, this academic software (it is well beyond my coding capability, and I don't have the source code anyway) may not have a delay in the way that it tries to communicate via TCP/IP. What I think has happened is that as network speed has increased, from 10/100Mbps, when it was written, to 1000Mbps currently, the software is reacting too fast to any, normally inconsequential, 'hiccip' in the network, incorrectly detects a communications failure and then crashes. A question, without a spot in DHCP Address Reservation, if I set a Static IP on the network adaptor side, would that PC actually get its requested IP?  I had assumed that I needed either a) both the Static IP and the DHCP Address Reservation or b) just DHCP Address Reservation?   regards Justin   ... View more