I have tried almost every VOIP soft phone app on Google Play. Before I found GS Wave, I reckoned Zoiper app was the best soft phone, thus I paid for its premium version to get its premium feature of video call.
However I never got this feature working. I wanted to see the video from my video door phone on my mobile with Zoiper. My video door phone supports H264 video codec but Zoiper supports VP8 unless I pay Zoiper again just for H264 codec . Unlike audio codec while a VOIP server can translate audio codec between clients, video codec is said to be P2P. (There may be a way of video codec translation, but I don’t know how.)
I had video calls working between my video door phone and desktop SIP phones which are “hard phones” with H264 built in. And I had audio calls working on all devices. So I was not desperate for video on Zoiper.
Zoiper has a major defect. It cannot stay online 24/7 on latest Android version (I tested on two Huawei Mate 8 and one P9) or iOS. Many times status bar shows it is online but actually it is not reachable. Zoiper was reliable on Android 4.x.x. I guess Zoiper “forgets” to re-register itself when OS goes into sleep. For above reasons I am reluctant to pay Zoiper any more money.
Recently I visited Fanvil website and discovered Fanvil had developed a soft phone called “Vdroid” for free download. To my surprise, Vdroid integrated G729 audio codec and H264 video codec. They are premium codec as on Zoiper. (Later on I learnt G729 patent expired on 1st Jan, 2017 but Zoiper is still selling G729 for money. I knew nothing about H264.) However Vdroid has too many bugs and is not a mature software.
Then I thought other VOIP device manufacturers might have their own soft phones for public. I checked Grandstream, Yealink and Cisco but only found Grandstream generously offering GS Wave. GS Wave has both Android and iOS version, and both works reliably, and both has G729 and H264 built in for free! I cannot wait any longer to recommend GS Wave to everyone. Google Play is overwhelmed by other apps for search results of “sip” or “voip”, and GS Wave is nowhere in the ranking. But trust me, it is the best one.
但是我还是决定换点什么看看。我有几个超级强悍的放大器，去年 Wickes clearance 时预存的货，但是由于新放大器采用更可靠的 F type 接口，而老放大器用的是普通 TV 插头，换放大器意味着全部线头要重做。我想放大器失效的可能性较小，同时也想偷懒，所以这次先换天线。我认为当初电视天线安装公司装的天线不够灵敏，才造成这信号时好时不好的问题。经过一番挑选，买了一款高增益、体积也是巨无霸型的天线。
贯穿楼层我只铺了一根馈线，当发现 AP 的双频是分路输出后，我开始寻找双频合路的元器件。可是这么专业的东西不好找啊，万能的淘宝确实有卖，但只有一家，似乎卖家已黄了，总不在线。百度百科上说功分器就是合路器，我就尝试反用了腔体功分器将双频合路，激动地发现这么廉价的元器件和简单的方法也能成功合路传输双频信号。于是感慨三件事：百度也有靠谱的时候、便宜也有好货、实践出真知。前二者未必总是为真，但第三者永远正确。
Windows 标准用户，利用 OpenVPN GUI 调用存放在 config 目录下的 ovpn 配置文件，连接任何一台服务器都有问题：能完成连接，但无法解析域名。
Windows 标准用户，右击 ovpn 文件，选单 Start OpenVPN on this config file，连接一台服务器无问题，连接另一台有问题：能完成连接，但无法解析域名。
Windows 管理员，利用 OpenVPN GUI 调用存放在 config 目录下的 ovpn 配置文件，连接任何一台服务器都无问题。虽然连接过程中有很多行显示“write UDPv4: No Route to Host (WSAEHOSTUNREACH) (code=10065) ”，但不影响最终成功连接。
Windows 管理员，右击 ovpn 文件，选单 Start OpenVPN on this config file，连接任何一台服务器都有问题：连接后能解析域名，但 IP 仍为原 IP——连了跟没连一样。
上述四种情况下都会有“write UDPv4: No Route to Host (WSAEHOSTUNREACH) (code=10065) ”出现。我曾尝试以此为线索解决无法解析域名的问题，有人说“changing the MTU value of the bridge interface to 1492”，可以在 Linux 下解决解析问题，但在 Windows 下仍无法解析。我觉得即使在 Linux 下能行，也是瞎猫碰到了死老鼠，真正原因未必是 MTU。