Timeouts to licence validation server

Having a peculiar issue. I run in modem mode usually, but for the sake of testing am currently in router mode and have the device connected directly to a port. I have disabled the Hub 5's firewall for the sake of testing.

I run software that checks every 10 minutes against a Cloudflare hosted licence validation server. This software runs multiple 'workers' (for the sake of discussion) within each instance and each worker has it's own licence and thus licence validation check every 10 minutes.

For some reason, regardless of router/modem mode if I run an instance with 60 'workers' there seems to be a 3/4 chance that the licence validation checks will time out regardless even though connectivity on the device doesn't falter.

if I run 3 instances with 20 each and stagger the starts by 1 minute it doesn't falter. Constant pings to the Cloudflare IPs show from the same machine show there are no drops when this occurs with the single instance. HTTP logging n the software shows error messages for anything that actually goes wrong in transport, but that isn't even happening, Virgin is somehow blocking these requests when they hit in bursts like this.

Firewall options don't change this behaviour and other users of the software (not on VM) are able to run single instances with 200+ 'workers' each.

How can I fix this? It's really taxing on the hardware to run multiple instances instead 1 with a large amount of workers. Any sort of IP flood detection shouldn't play into things in Modem mode anyway surely, and currently it's disabled fully on the router mode but still happening.

Any help would be muchly appreciated.