Slow 4G connection only, but only sometimes -- SOLVED

This has been an interesting thread. I got the T-Mobile GW on the beta program back in early January  and the GW ran solid until the end of June with little to no attention. Speeds were relatively good so I did not take a great deal of focus on mine. Then in July repeated tower disconnects of both the primary and secondary signal became a daily frustration. I did a fair amount of investigation and tinkered with my T-Mobile GW/router for weeks. I made 4 support calls and did a great deal of investigating. In my case the tower, i finally confirmed, is 5.3 miles line of sight with no obstructions. The primary signal always locks on B2 and the secondary signal picks up on n71. Well, I could see the RSRP and RSRQ and SNR values were commonly in the good to excellent range but the signal drops over and over were irritating. In my investigations I came across the waveform.com site and they have an very good guide about the device and a step by step for connecting an external MIMO antenna to the router. Well, once I paid attention to the design of the router it gave me ideas. If you examine the device you can see there are 4 5G antennas and 4 WIFI antennas and they are clearly labeled. What I took away from that was a more detailed investigation of systematically rotating the can to influence the exposure of the antenna responsible for the 5G n71 connection. I found I could give up a bar on the B2 LTE signal and pick up 4 bars on the 5G n71 and low and behold the speed tests improved nicely. While testing i used a Linux client to run concurrent PINGs to 8.8.8.8 9.9.9.9 & 1.1.1.1, i.e. google, quad9, and cloud flare DNS servers. When the disconnects took place is was obvious and the PING latency for each was easy to compare and get a clear picture of when the tower connection returned and improved or became unstable. For the investigation of how the gateway was running I used my MacBook Pro with a CAT 6 cable connected direct to the router on LAN1. The HTML interface on a computer is much better than the mobile application though it lacks advanced functionality it really needs. The overview and status pages were quite helpful in getting better visibility to operation. Knowing the signal strength, signal quality and signal to noise ratio are really helpful in understanding what your connections are doing. I recorded the values over and over and evaluated operation when the unit would ONLY pick up the primary B2 channel and fail to maintain any connection to the n71 channel. Once I started experimenting with rotating the can to influence the signal wash over the various antennas I discovered how much that could help. I read about others complaining about heat and the influence of heat on operation so I put my router outside on the patio, in the shade under the second story deck above in 88 degree weather and for 5 hours it ran solid without a single signal drop for a period of time. It never threw any alarms for over heating. Sure it was running warmer when I brought it in but it returned to a cooler state and suffered no ill effects. The testing was done to confirm, in my mind, that the location inside the glass door was still a good place or not to have it. Given the download speeds of 157-170 Mbs and 50+ Mbs upload testing with speedtest.net I feel it is doing pretty well. The key though to getting it to favor the n71 channel. Upon the fourth call with T-Mobile the support engineer did confirm that they had received multiple trouble calls on that tower and were upgrading it. I had seen the disruptions and even on Monday morning when the T-Mobile engineer contacted me it bounced but after that it has been stable. The take away for me is that being out on the edge of the range of the signal where it is still in the good range and has good to excellent signal quality means that if I decide to buy the external MIMO antenna I can probably improve the communication 3-4 dBm and not have to be so concerned about having it in a specific window. It will also allow better utilization of the 2.4 and 5 ghz WIFI signals in the house. I have seen pretty good signal strength with the router either centered upstairs or downstairs and I am using it to cover 3300 square feet of home on two levels. Actually I am pretty impressed with the unit though I do feel the antenna design might be a bit limiting. If you slip the outer shell off and look at it the antenna layout is super obvious as it is all tagged for 5G-1, 5G-2 etc… and WIFI-1, WIFI-2, etc… After seeing the document at waveform.com a neighbor told me he had dropped his SIM into the replacement router by mistake and it was stuck somewhere in the can. Well, I have handled networking gear for 22 years so I offered to get the SIMs out of it. That is when I got a real good look at the design of the router. My take away is that if you need to remove and replace a SIM, as was the case here, be sure to have the router on its side with the SIM carrier so the retention screw is to the right of the SIM when you carefully remove the nano SIM. If you turn the can upside down and try to remove the SIM it can fall right out of the carrier and into the slot and get stuck in there. It was fairly simple to get it out but it took some small tweezers and care to get it to come back out. The SIM carrier does NOT hold the nano SIM at all. The SIM card just rest on the carrier and can easily fall out or off the carrier. From what I could see it is a pretty simple task to connect an external MIMO antenna to the router and that would probably make many marginal installations better. We are in rural East TN with pastures and farms between us and the tower so I don't expect much more but the T-Mobile home internet router solution is 10X the speed I had in CA with bonded DSL lines and $25/month less. My only other option was Hughes net, so well, that was not going to happen. They would have been $20 more per month after two months with a 2 year contract for a solution with higher latency. Duh… not on my watch.  Now that the tower upgrade was done it appears to be a positive improvement. Like previous posts in this thread it is my hope that if anyone reads this and it helps them to improve their solution then it is worth the time sharing as T-Mobile support can help customers some but we can also help one another.