I have an Asus RT-AC3100 running Merlin 380.59. I am attempting to enable link aggregation (LAG / LACP / IEEE 802.3ad / Port Teaming... whatever you prefer to call it) to an Adtran Netvanta 1534 (2nd Generation) switch running the newest firmware, R11.13.0. The Asus has no configuration options to speak of, simply an on/off switch in the GUI. I have configured everything in the Netvanta per Adtran's support materials. Each individual link works just fine when alone whether LAG is enabled or disabled. With LAG enabled on the switch and the router, everything works when one link is up and the other down (doesn't matter which link). I don't know that it is pertinent, but my network is entirely CAT6. All patch cables have been tested with a cable tester. I can establish gigabit connections without a problem in the absence of link aggregation.
The problem occurs when I attempt to actually use both links in aggregation. I lose the ability to access certain LAN assets, including the Adtran switch. Routing seems to just go all wonky. I realize that isn't a technical term, but I'm not really an expert. I can confirm that STP is not blocking either links port on either device (obviously the purpose of LAG is to stop STP from thinking there is a network loop). Accessing external sites (websites or connecting via VPN to a separate network) becomes erratic at best. Oddly, any devices "upstream" of the switch, those connected directly to the router either by physical link or wirelessly, function just fine and can access the switch or other downstream devices on the switch's network.
I am at a loss. Does anyone have any suggestions on how to get link aggregation properly functioning between the switch and the router?
