There's something weird going on with 3.8.9.2. Routers configured with this are generating errors on our Sonicwall firewall when we attempt to remotely manage them. 3.8.8.2 is fine. Errors are all to do with TCP packets with invalid option lengths:
TCP packet received with invalid option length; TCP packet dropped
TCP packet received with invalid Window Scale option length; TCP packet dropped
TCP packet received with invalid SACK option length; TCP packet dropped
Anyone else seeing this sort of thing at all, please? The net effect is that the web interface either loads very slowly and incompletely, or does not load at all .

Cheers,

Nick

Is the MTU size set correctly for the WAN ?

I've seen it set as 1500 as the default on occasions.

If using VPN's or fancy SDN's may need this decreasing from the common 1492 normally used.

Thanks for the thought; unfortunately VPNs aren't an issue - we're not using them for these routers. They're there to provide internet connectivity for building management systems; we just need to be able to manage them remotely. The MTU is set to 1520, so it may be worth knocking it down, however; I'll give it a go.

MTU might be right - testing shows it does need dropping, and quite substantially.

OK, dropped it to 1446 and I'm still getting the TCP errors at the firewall here, but overall it's more reliable and response is snappier.

Nick

Have this problem been sorted as I also am getting this issue.